Document:

Exhibit
10.5.1

 

_______
__, 2018

 

Gentlemen:

 

Allegro
Merger Corp. (“Corporation”), a blank check company formed for the purpose of acquiring one or more businesses or
entities (a “Business Combination”), intends to register its securities under the Securities Act of 1933, as amended
(“Securities Act”), in connection with its initial public offering (“IPO”).

 

The
undersigned hereby commits to purchase an aggregate of ___ units of the Corporation (“Placement Units”), each Placement
Unit currently intended to consist of one share of common stock, par value $0.0001 per share (“Common Stock”), of
the Corporation, and one-half of one warrant to purchase one share of Common Stock, at $10.00 per Private Unit, for an aggregate
purchase price of $______ (the “Purchase Price”). Simultaneously with the execution of this agreement, the undersigned
will cause the Purchase Price to be delivered to Graubard Miller, counsel for the Corporation (“Counsel”), by wire
transfer as set forth in the instructions attached as Exhibit A to hold in an interest bearing account until the Corporation consummates
the IPO, together with an originally executed Form W-9 or W-8BEN (or other similar applicable form). The undersigned acknowledges
and agrees that if the underwriters in the IPO determine based on market conditions at that time that additional Placement Units
must be purchased in order to consummate the IPO, the undersigned will purchase a proportionate number of additional Placement
Units, pro rata with the other holders of Placement Units. If additional purchases are necessary, the undersigned agrees that
it will deliver the purchase price for such additional Placement Units to Counsel as promptly as is reasonably practicable following
written notice from the Corporation of such decision. In the event that the undersigned breaches the purchase obligations set
forth above to purchase the Placement Units and does not purchase all or any portion of such additional Placement Units, the other
purchasers of the Placement Units will have the ability, but not the obligation, to satisfy the undersigned’s purchase obligation
(and if they do, then the undersigned will sell, at the original cost, the Insider Shares (defined below) held by the undersigned
to the other purchasers of Placement Units who satisfy the undersigned’s purchase obligation and shall thereupon have no
further liability or obligation in relation to such breach).

 

The
consummation of the purchase and issuance of the Placement Units shall occur simultaneously with the consummation of the IPO.
Simultaneously with the consummation of the IPO, Counsel shall (i) deposit the Purchase Price, without interest or deduction,
into the trust fund (“Trust Fund”) established by the Corporation for the benefit of the Corporation’s public
stockholders as described in the Corporation’s registration statement filed in connection with the IPO (“Registration
Statement”) and (ii) deliver all interest earned on the Purchase Price and any remaining unused portion of the Purchase
Price (in the event the number of Placement Units required by the underwriters to be purchased by the undersigned and the other
purchasers of the Private Units is reduced, which such reduction will be effectuated pro rata with all other purchasers of Private
Units) to the undersigned. If the Corporation does not complete the IPO within six (6) months from the date of this letter (subject
to a six (6) month extension at the Corporation’s option in its sole discretion), the Purchase Price (plus interest earned
thereon) will be returned to the undersigned.

 

     

     

    

 

Each
of the Corporation and the undersigned acknowledges and agrees that Counsel is serving hereunder solely as a convenience to the
parties to facilitate the purchase of the Placement Units and Counsel’s sole obligation under this letter agreement is to
act with respect to holding and disbursing the Purchase Price for the Placement Units as described above. Counsel shall not be
liable to the Corporation or the undersigned or any other person or entity in respect of any act or failure to act hereunder or
otherwise in connection with performing its services hereunder unless Counsel has acted in a manner constituting gross negligence
or willful misconduct. The Corporation and Eric S. Rosenfeld, jointly and severally, shall indemnify Counsel against any claim
made against it (including reasonable attorney’s fees) by reason of it acting or failing to act in connection with this
letter agreement except as a result of its gross negligence or willful misconduct. Counsel may rely and shall be protected in
acting or refraining from acting upon any written notice, instruction or request furnished to it hereunder and believed by it
to be genuine and to have been signed or presented by the proper party or parties.

 

In
consideration of the above purchase obligations, Eric S. Rosenfeld or an affiliate of his (the “Transferor”) hereby
agrees to transfer to the undersigned an aggregate of _____ shares of Common Stock (“Insider Shares”) of the Corporation
at approximately $___ per Insider Share, for an aggregate purchase price of $___, which amount is being delivered to the Transferor
simultaneously with the execution of this letter. The undersigned acknowledges and agrees that if the underwriters in the IPO
determine the size of the offering should be increased or decreased, the undersigned will either receive a dividend on the Insider
Shares transferred hereunder or contribute a portion of the Insider Shares back to capital, as applicable, in order to maintain
the aggregate ownership of the Corporation’s initial stockholders at a certain percentage of the number of shares to be
sold in the IPO. Any increase or decrease will affect all holders of Insider Shares on a pro-rata basis.

 

The
Insider Shares will be identical to the shares of Common Stock included in the units to be sold by the Corporation in the IPO,
and the Placement Units will be identical to the units to be sold by the Corporation in the IPO, except that:

 

		●	the
                                         undersigned agrees to vote the Insider Shares and shares of Common Stock included in
                                         the Placement Units (the “Placement Shares”) in favor of any proposed Business
                                         Combination;

 

		●	the
                                         undersigned agrees not to seek conversion rights, or seek to sell such shares in any
                                         tender offer, with respect to any Insider Shares and Placement Shares;

 

    	 	2	 

     

    

 

		●	the
                                         Insider Shares will be placed in escrow, subject to the terms of an escrow agreement
                                         reasonably acceptable to the undersigned, and will not be released (subject to certain
                                         exceptions) until one year after the completion of a Business Combination, and may only
                                         be transferred during this time period (i) among the initial purchasers of the Insider
                                         Shares, to the Corporation’s officers, directors and employees, to a holder’s
                                         affiliates, or to its members upon its liquidation, (ii) to relatives and trusts for
                                         estate planning purposes, (iii) by virtue of the laws of descent and distribution upon
                                         death, (iv) pursuant to a qualified domestic relations order, (v) by certain pledges
                                         to secure obligations incurred in connection with purchases of the Corporation’s
                                         securities, (vi) by private sales made at or prior to the consummation of a Business
                                         Combination at prices no greater than the price at which the Insider Shares were originally
                                         purchased or (vii) to the Corporation for cancellation in connection with the consummation
                                         of a Business Combination, in each case (except for clause (vii) or with the Corporation’s
                                         prior consent) where the transferee agrees to the terms of the escrow agreement;

 

		●	the
                                         Placement Units and underlying securities will not be transferable (except (i) among
                                         the initial purchasers of the Placement Units, to the Corporation’s officers, directors
                                         and employees, to a holder’s affiliates, or to its members upon its liquidation,
                                         (ii) to relatives and trusts for estate planning purposes, (iii) by virtue of the laws
                                         of descent and distribution upon death, (iv) pursuant to a qualified domestic relations
                                         order, (v) by certain pledges to secure obligations incurred in connection with purchases
                                         of the Corporation’s securities, (vi) by private sales made in connection with
                                         the consummation of a Business Combination at prices no greater than the price at which
                                         the Placement Units were originally purchased or (vii) to the Corporation for cancellation
                                         in connection with the consummation of a Business Combination, in each case (except for
                                         clause (vii) or with the Corporation’s prior consent) where the transferee agrees
                                         to the terms of the transfer restrictions) until 30 days after the completion of a Business
                                         Combination;

 

		●	the
                                         Insider Shares and Placement Units (and underlying securities) will be subject to customary
                                         registration rights, which shall be described in the Registration Statement;

 

		●	the
                                         Undersigned will not participate in any liquidation distribution with respect to the
                                         Insider Shares or Placement Units (but will participate in liquidation distributions
                                         with respect to any units or shares of Common Stock purchased by the undersigned in the
                                         IPO or in the open market after the IPO) if the Corporation fails to consummate a Business
                                         Combination; and

 

    	 	3	 

     

    

 

		●	the
                                         Insider Shares and Placement Units will include any additional terms or restrictions
                                         as is customary in other similarly structured blank check company offerings or as may
                                         be reasonably required by the underwriters in the IPO in order to consummate the IPO,
                                         each of which will be set forth in the Registration Statement.

 

The
undersigned further acknowledges and agrees that if, in order to consummate any Business Combination, the holders of Insider Shares
or Placement Units are required to contribute back to the capital of the Corporation a portion of any such securities to be cancelled
by the Corporation, the undersigned will contribute back to the capital of the Corporation a proportionate number of Insider Shares
or Placement Units, as applicable, pro rata with the other holders of Insider Shares or Placement Units, as applicable.

 

The
undersigned acknowledges and agrees that he will execute agreements in form and substance typical for transactions of this nature
necessary to effectuate the foregoing agreements and obligations prior to the consummation of the IPO as are reasonably acceptable
to the undersigned, including but not limited to (i) an insider letter, (ii) an escrow agreement and (iii) a registration rights
agreement.

 

The
undersigned hereby represents and warrants that, as applicable:

 

		(a)	he
                                         has been advised that the Insider Shares and Placement Units have not been registered
                                         under the Securities Act;

 

		(b)	he
                                         is acquiring the Insider Shares and Placement Units for his account for investment purposes
                                         only;

 

		(c)	he
                                         has no present intention of selling or otherwise disposing of the Insider Shares and
                                         Placement Units in violation of the securities laws of the United States;

 

		(d)	he
                                         is an “accredited investor” as defined by Rule 501 of Regulation D promulgated
                                         under the Securities Act of 1933, as amended;

 

		(e)	he
                                         has had both the opportunity to ask questions and receive answers from the officers and
                                         directors of the Corporation and all persons acting on its behalf concerning the terms
                                         and conditions of the offer made hereunder;

 

		(f)	he
                                         is familiar with the proposed business, management, financial condition and affairs of
                                         the Corporation;

 

		(g)	he
                                         has full power, authority and legal capacity to execute and deliver this letter and any
                                         documents contemplated herein or needed to consummate the transactions contemplated in
                                         this letter; and

 

    	 	4	 

     

    

 

		(h)	this
                                         letter constitutes the legal, valid and binding obligation of the undersigned and is
                                         enforceable against him.

 

	 	Very truly yours,
	 	 
	 	 

 

Accepted
and Agreed:

 

ALLEGRO
MERGER CORP.

 

	By:	 	 
	 	Name:	 
	 	Title:	 
	 	 	 
	 	 
	ERic s. rosenfeld	 

 

Graubard
miller

(solely
with respect to its obligations to hold

and
disburse monies for the Placement Units)

 

	By:	 	 
	 	Name:	 
	 	Title:	 

 

 

5Exhibit 10.5.2

 

UNIT
SUBSCRIPTION AGREEMENT

 

This
UNIT SUBSCRIPTION AGREEMENT (this “Agreement”) is made as of the [__] day of June 2018, by and between
Allegro Merger Corp., a Delaware corporation (the “Company”), having its principal place of business at 777
Third Avenue, 37th Floor, New York, New York 10017, and the subscribers set forth on Schedule A hereto (the “Subscribers”).

 

WHEREAS,
the Company desires to sell on a private placement basis (the “Offering”) an aggregate of 372,500 units (“Units”)
of the Company, each Unit comprised of one share of common stock of the Company, par value $0.0001 per share (“Common
Stock”), one right (“Right”) to receive one-tenth (1/10) of one share of common stock upon the consummation
of the Company’s initial business combination (the “Business Combination”), and one warrant to purchase
one share of Common Stock (“Warrant”), for a purchase price of $3,725,000, or $10.00 per Unit. The shares of
Common Stock underlying the Rights are hereinafter referred to as the “Right Shares.”  The shares
of Common Stock underlying the Warrants are hereinafter referred to as the “Warrant Shares.”  The
shares of Common Stock underlying the Units (excluding the Right Shares and Warrant Shares) are hereinafter referred to as the
“Placement Shares.” The Rights underlying the Units are hereinafter referred to as the “Placement
Rights.”  The Warrants underlying the Units are hereinafter referred to as the “Placement Warrants.”  The
Units, Placement Shares, Placement Rights, Right Shares, Placement Warrants and Warrant Shares, collectively, are hereinafter
referred to as the “Securities.”  The exercise price for any Warrant Share shall be $11.50. Subject
to the foregoing, the Placement Warrants are exercisable during the period commencing on the later of (i) twelve (12) months from
the date of the completion of the Company’s initial public offering of units (the “IPO”) and (ii) 30
days following the consummation of the Business Combination and expiring on the fifth anniversary following consummation of the
Business Combination; and

 

WHEREAS,
each Subscriber wishes to purchase the number of Units set forth on Schedule A hereto and the Company wishes to accept
such subscription from each Subscriber.

 

NOW,
THEREFORE, in consideration of the premises and the mutual covenants hereinafter set forth and other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the Company and the Subscribers hereby agree as follows:

 

	 	1.	Agreement
    to Subscribe.

 

1.1
Purchase and Issuance of the Units. Upon the terms and subject to the conditions of this Agreement, each Subscriber hereby
agrees to purchase from the Company, and the Company hereby agrees to sell to each Subscriber, on the Closing Date (as defined
below), the number of Units set forth on Schedule A for its pro rata portion of the aggregate purchase price of $500,000
(the “Purchase Price”).

        

1.2
Delivery of the Purchase Price.  Upon execution of this Agreement, the Company is hereby bound to fulfill its obligations
hereunder and each Subscriber hereby commits to deliver into a trust account (the “Trust Account” )
held at JP Morgan Chase Bank, N.A. or any other financial institution chosen by the Company, with Continental Stock Transfer &
Trust Company acting as trustee (“Continental”), its pro rata portion of the Purchase Price in immediately
available funds by wire transfer or such other form of payment as shall be acceptable to the Trustee, in its sole and absolute
discretion, at Closing (as defined below).

 

1.3
Closing. The closing of the Offering (the “Closing”), shall take place at the offices of Graubard
Miller simultaneously with, and is contingent upon, the closing of the IPO on or before September 30, 2018 (the “Closing
Date”).

 

1.4
Termination.  This Agreement and each of the obligations of the undersigned shall be null and void and without effect
if the Closing does not occur prior to September 30, 2018.

 

     

     

    

 

	 	2.	Representations
    and Warranties of Subscribers.

 

Each
Subscriber represents and warrants to the Company that:

 

2.1
No Government Recommendation or Approval.  Subscriber understands that no federal or state agency has passed upon
or made any recommendation or endorsement of the Company or the Offering of the Securities.

 

2.2
Accredited Investor. Subscriber represents that it is an “accredited investor” as such term is defined in
Rule 501(a) of Regulation D under the Securities Act of 1933, as amended (the “Securities Act”), and acknowledges
that the sale contemplated hereby is being made in reliance, among other things, on a private placement exemption to “accredited
investors” under the Securities Act and similar exemptions under state law.

 

2.3
Intent.  Subscriber is purchasing the Securities solely for investment purposes, for such Subscriber’s own
account (and/or for the account or benefit of its members or affiliates, as permitted, pursuant to the terms hereof), and not
with a view to the distribution thereof and Subscriber has no present arrangement to sell the Securities to or through any person
or entity except as may be permitted hereunder.  Subscriber shall not engage in hedging transactions with regard to
the Securities unless in compliance with the Securities Act.

 

2.4
Restrictions on Transfer.  Subscriber acknowledges and understands the Units are being offered in a transaction
not involving a public offering in the United States within the meaning of the Securities Act.  The Securities have
not been registered under the Securities Act and, if in the future Subscriber decides to offer, resell, pledge or otherwise transfer
the Securities, such Securities may be offered, resold, pledged or otherwise transferred only (i) pursuant to an effective
registration statement filed under the Securities Act, (ii) pursuant to an exemption from registration under Rule 144 promulgated
under the Securities Act, if available, or (iii) pursuant to any other available exemption from the registration requirements
of the Securities Act, and in each case in accordance with any applicable securities laws of any state or any other jurisdiction.
Notwithstanding the foregoing, Subscriber acknowledges and understands the Securities are subject to transfer restrictions as
described in Section 8 hereof.  Subscriber agrees that if any transfer of its Securities or any interest therein is
proposed to be made, as a condition precedent to any such transfer, Subscriber may be required to deliver to the Company an opinion
of counsel satisfactory to the Company with respect to such transfer. Absent registration or another available exemption from
registration, Subscriber agrees it will not transfer the Securities (unless otherwise permitted pursuant to the terms hereof).  Subscriber
further acknowledges that because the Company is a shell company, Rule 144 may not be available to Subscriber for the resale of
the Securities until the one year anniversary following consummation of the Business Combination, despite technical compliance
with the requirements of Rule 144 and the release or waiver of any contractual transfer restrictions.

 

2.5
Sophisticated Investor.

 

(i)  Subscriber
is sophisticated in financial matters and is able to evaluate the risks and benefits of the investment in the Securities.

 

(ii)
Subscriber is aware that an investment in the Securities is highly speculative and subject to substantial risks because, among
other things, (a) the Securities are subject to transfer restrictions and have not been registered under the Securities Act and
therefore cannot be sold unless subsequently registered under the Securities Act or an exemption from such registration is available
and (b) Subscriber has waived its redemption rights with respect to the Securities as set forth in Section 5 hereof, and the Securities
held by Subscriber are not entitled to, and have no right, interest or claim to any monies held in the Trust Account, and accordingly
Subscriber may suffer a loss of a portion or all of its investment in the Securities. Subscriber is able to bear the economic
risk of its investment in the Securities for an indefinite period of time.

 

2.6
Independent Investigation.  Subscriber, in making the decision to purchase the Units, has relied upon an independent
investigation of the Company and has not relied upon any information or representations made by any third parties or upon any
oral or written representations or assurances from the Company, its officers, directors or employees or any other representatives
or agents of the Company, other than as set forth in this Agreement. Subscriber is familiar with the business, operations and
financial condition of the Company and has had an opportunity to ask questions of, and receive answers from the Company’s
officers and directors concerning the Company and the terms and conditions of the offering of the Units and has had full access
to such other information concerning the Company as Subscriber has requested. Subscriber confirms that all documents that it has
requested have been made available and that Subscriber has been supplied with all of the additional information concerning this
investment which Subscriber has requested.

 

    	 	2	 

     

    

 

2.7
Organization and Authority.  Subscriber is duly organized, validly existing and in good standing under the laws
of the State of New York and it possesses all requisite power and authority necessary to carry out the transactions contemplated
by this Agreement.

 

2.8
Authority. This Agreement has been validly authorized, executed and delivered by Subscriber and is a valid and binding
agreement enforceable in accordance with its terms, except as such enforceability may be limited by applicable bankruptcy, insolvency,
fraudulent conveyance, moratorium, reorganization, or similar laws relating to, or affecting generally the enforcement of, creditors’
rights and remedies or by equitable principles of general application and except as enforcement of rights to indemnity and contribution
may be limited by federal and state securities laws or principles of public policy.

 

2.9
No Conflicts. The execution, delivery and performance of this Agreement and the consummation by Subscriber of the transactions
contemplated hereby do not violate, conflict with or constitute a default under (i) Subscriber's charter documents, (ii) any
agreement or instrument to which Subscriber is a party or (iii) any law, statute, rule or regulation to which Subscriber is subject,
or any agreement, order, judgment or decree to which Subscriber is subject, except as would not be material to Subscriber’s
performance of its obligations hereunder.

 

2.10
No Legal Advice from Company.  Subscriber acknowledges it has had the opportunity to review this Agreement and the
transactions contemplated by this Agreement and the other agreements entered into between the parties hereto with Subscriber’s
own legal counsel and investment and tax advisors.  Except for any statements or representations of the Company made
in this Agreement and the other agreements entered into between the parties hereto, Subscriber is relying solely on such counsel
and advisors and not on any statements or representations of the Company or any of its representatives or agents for legal, tax
or investment advice with respect to this investment, the transactions contemplated by this Agreement or the securities laws of
any jurisdiction.

 

2.11
Reliance on Representations and Warranties.  Subscriber understands the Units are being offered and sold to Subscriber
in reliance on exemptions from the registration requirements under the Securities Act, and analogous provisions in the laws and
regulations of various states, and that the Company is relying upon the truth and accuracy of the representations, warranties,
agreements, acknowledgments and understandings of Subscriber set forth in this Agreement in order to determine the applicability
of such provisions.

 

2.12
No General Solicitation.  Subscriber is not subscribing for the Units as a result of or subsequent to any general
solicitation or general advertising, including but not limited to any advertisement, article, notice or other communication published
in any newspaper, magazine, or similar media or broadcast over television or radio, or presented at any seminar or meeting or
in a registration statement with respect to the IPO filed with the Securities and Exchange Commission (“SEC”).

 

2.13
Legend.  Subscriber acknowledges and agrees the certificates evidencing each of the Securities shall bear a restrictive
legend (the “Legend”), in form and substance substantially as set forth in Section 4 hereof.

 

	 	3.	Representations,
    Warranties and Covenants of the Company.

 

The
Company represents and warrants to, and agrees with, each Subscriber that:

 

3.1
Valid Issuance of Capital Stock. The total number of shares of all classes of capital stock which the Company has authority
to issue is 40,000,000 shares of Common Stock and 1,000,000 shares of preferred stock, $0.0001 par value per share (“Preferred
Stock”). As of the date hereof, the Company has issued and outstanding 3,737,500 shares of Common Stock (of which up
to 487,500 shares are subject to forfeiture) and no shares of Preferred Stock. All of the issued shares of capital stock of the
Company have been duly authorized, validly issued, and are fully paid and non-assessable.

 

3.2
Title to Securities.  Upon issuance in accordance with, and payment pursuant to, the terms hereof, the rights agreement
to be entered into between the Company and the rights agent in connection with the IPO (the “Rights Agreement”)
and the warrant agreement to be entered into between the Company and the warrant agent in connection with the IPO (the “Warrant
Agreement”), as the case may be, each of the Units, Placement Shares, Placement Rights, Right Shares, Placement Warrants
and the Warrant Shares will be duly and validly issued, fully paid and non-assessable. On the date of issuance of the Units, the
Right Shares and Warrant Shares shall have been reserved for issuance. Upon issuance in accordance with, and payment pursuant
to, the terms hereof, the Rights Agreement and the Warrant Agreement, as the case may be, Subscriber will have or receive good
title to the Units, Placement Shares, Placement Rights and Placement Warrants, free and clear of all liens, claims and encumbrances
of any kind resulting from actions of, or any failure to act by, the Company, other than (i) transfer restrictions hereunder and
(ii) transfer restrictions under federal and state securities laws.

 

    	 	3	 

     

    

        

3.3
Organization and Qualification. The Company is a corporation duly incorporated, validly existing and in good standing
under the laws of the State of Delaware and has the requisite corporate power to own its properties and assets and to carry on
its business as now being conducted.

 

3.4
Authorization; Enforcement. (i) The Company has the requisite corporate power and authority to enter into and perform
its obligations under this Agreement and to issue the Securities in accordance with the terms hereof, (ii) the execution,
delivery and performance of this Agreement by the Company and the consummation by it of the transactions contemplated hereby have
been duly authorized by all necessary corporate action, and no further consent or authorization of the Company or its Board of
Directors (the “Board”) or stockholders is required, and (iii) this Agreement constitutes a valid and
binding obligation of the Company enforceable against the Company in accordance with its terms, except as such enforceability
may be limited by applicable bankruptcy, insolvency, fraudulent conveyance, moratorium, reorganization, or similar laws relating
to, or affecting generally the enforcement of, creditors’ rights and remedies or by equitable principles of general application
and except as enforcement of rights to indemnity and contribution may be limited by federal and state securities laws or principles
of public policy.

 

3.5
No Conflicts. The execution, delivery and performance of this Agreement and the consummation by the Company of the transactions
contemplated hereby do not (i) result in a violation of the Company’s certificate of incorporation or by-laws, (ii) conflict
with, or constitute a default under any agreement or instrument to which the Company is a party or (iii) violate any law statute,
rule or regulation to which the Company is subject or any agreement, order, judgment or decree to which the Company is subject
or by which it is bound. Other than any SEC or state securities filings which may be required to be made by the Company subsequent
to the Closing, and any registration statement which may be filed pursuant thereto, the Company is not required under federal,
state or local law, rule or regulation to obtain any consent, authorization or order of, or make any filing or registration with,
any court or governmental agency or self-regulatory entity in order for it to perform any of its obligations under this Agreement
or issue the Units, Placement Shares, Placement Rights, Right Shares, Placement Warrants or the Warrant Shares in accordance with
the terms hereof.

 

	 	4.	Legends.

 

4.1
Legend. The Company will issue the Units, Placement Shares, Placement Rights and Placement Warrants, and, when issued, the
Right Shares and Warrant Shares, purchased by each Subscriber in the name of such Subscriber. The Securities will bear the following
Legend and appropriate “stop transfer” instructions:

 

“THE
SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”),
OR ANY STATE SECURITIES LAWS AND NEITHER THESE SECURITIES NOR ANY INTEREST THEREIN MAY BE OFFERED, SOLD, TRANSFERRED, PLEDGED
OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR SUCH LAWS OR AN EXEMPTION
FROM REGISTRATION UNDER THE SECURITIES ACT AND SUCH LAWS WHICH, IN THE OPINION OF COUNSEL FOR THIS CORPORATION, IS AVAILABLE.”

 

“THE
SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS ON TRANSFER PURSUANT TO A UNIT SUBSCRIPTION AGREEMENT BETWEEN
ALLEGRO MERGER CORP. (THE “COMPANY”) AND THE UNDERWRITERS OF THE COMPANY’S INITIAL PUBLIC OFFERING AND MAY ONLY
BE OFFERED, SOLD, TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED OF DURING THE TERM THEREOF PURSUANT TO THE TERMS SET FORTH IN THE
UNIT SUBSCRIPTION AGREEMENT.”

 

    	 	4	 

     

    

 

4.2
Subscribers’ Compliance. Nothing in this Section 4 shall affect in any way any Subscriber’s obligations
and agreements to comply with all applicable securities laws upon resale of the Securities.

 

4.3
Company’s Refusal to Register Transfer of the Securities.  The Company shall refuse to register any transfer
of the Securities if, in the sole judgment of the Company, such purported transfer would not be made (i) pursuant to an effective
registration statement filed under the Securities Act, or (ii) pursuant to an available exemption from the registration requirements
of the Securities Act and (iii) in compliance herewith.

 

4.4
Registration Rights.  Each Subscriber will be entitled to certain registration rights which will be governed by
a registration rights agreement (“Registration Rights Agreement”) to be entered into between, among others,
Subscribers and the Company, on or prior to the effective date of the registration statement filed in connection with the IPO,
as amended at the time it becomes effective (the “Registration Statement”). 

 

	 	5.	Waiver
    of Liquidation Distributions.

 

In
connection with the Securities purchased pursuant to this Agreement, each Subscriber hereby waives its redemption rights (i) in
connection with the Company’s consummation of the Business Combination, (ii) if the Company fails to consummate the Business
Combination or liquidates within 18 months from the completion of the Offering or (iii) if the Company seeks an amendment to its
amended and restated certificate of incorporation that would affect the substance or timing of the Company’s obligation
to redeem 100% of the Public Shares (as defined below).  If any Subscriber acquires shares of Common Stock in the IPO
or in the aftermarket (“Public Shares”), such Subscriber shall be eligible to redeem any Public Shares upon
the same terms offered to other holders of Common Stock purchased in the IPO.

 

	 	6.	Termination
    of Placement Rights and Placement Warrants.

 

6.1
Failure to Consummate Business Combination. The Placement Rights and Placement Warrants shall be terminated upon the
dissolution of the Company or in the event that the Company does not consummate the Business Combination within 18 months from
the completion of the IPO.

 

6.2
Termination of Rights as Holder. If the Placement Rights and Placement Warrants are terminated in accordance with Section 6.1,
then after such time each Subscriber (or its successor in interest) shall no longer have any rights as a holder of such Placement
Rights and Placement Warrants and the Company shall take such action as is appropriate to cancel such Placement Rights and Placement
Warrants. Each Subscriber hereby irrevocably grants the Company a limited power of attorney for the purpose of effectuating the
foregoing and agrees to take any and all measures reasonably requested by the Company necessary to effect the foregoing.

 

	 	7.	Rescission
    Right Waiver and Indemnification.

 

7.1 Each
Subscriber understands and acknowledges an exemption from the registration requirements of the Securities Act requires there be
no general solicitation of purchasers of the Units. In this regard, if the IPO were deemed to be a general solicitation with respect
to the Units, the offer and sale of such Units may not be exempt from registration and, if not, each Subscriber may have a right
to rescind its purchase of the Units. In order to facilitate the completion of the Offering and in order to protect the Company,
its stockholders and the amounts in the Trust Account from claims that may adversely affect the Company or the interests of its
stockholders, each Subscriber hereby agrees to waive, to the maximum extent permitted by applicable law, any claims, right to
sue or rights in law or arbitration, as the case may be, to seek rescission of its purchase of the Units to the extent that such
recession right results from actions of such Subscriber that result in the IPO being deemed a general solicitation with respect
to the Units. Each Subscriber acknowledges and agrees this waiver is being made in order to induce the Company to sell the Units
to such Subscriber. Each Subscriber agrees the foregoing waiver of rescission rights shall apply to any and all known or unknown
actions, causes of action, suits, claims or proceedings (collectively, “Claims”) and related losses, costs,
penalties, fees, liabilities and damages, whether compensatory, consequential or exemplary, and expenses in connection therewith,
including reasonable attorneys’ and expert witness fees and disbursements and all other expenses reasonably incurred in
investigating, preparing or defending against any Claims, whether pending or threatened, in connection with any present or future
actual or asserted right to rescind the purchase of the Units hereunder or relating to the purchase of the Units and the transactions
contemplated hereby.

 

    	 	5	 

     

    

 

7.2 Each
Subscriber agrees not to seek recourse against the Trust Account for any reason whatsoever in connection with its purchase of
the Units or any Claim that may arise now or in the future, provided that nothing herein shall preclude such Subscriber from making
any claim or seeking recourse against the funds held outside of the Trust Account or seeking payment of any deferred underwriting
fee due and payable pursuant to the underwriting agreement for the IPO.

 

7.3 Each
Subscriber acknowledges and agrees that the stockholders of the Company are and shall be third-party beneficiaries of this Section
7. 

 

7.4 Each
Subscriber agrees that, to the extent any waiver of rights under this Section 7 is ineffective as a matter of law, such Subscriber
has offered such waiver for the benefit of the Company as an equitable right that shall survive any statutory disqualification
or bar that applies to a legal right. Each Subscriber acknowledges the receipt and sufficiency of consideration received from
the Company hereunder in this regard.

 

	 	8.	Terms
    of the Units.

 

The
Units and their component parts are substantially identical to the units to be offered in the IPO except that: (i) the Units and
their component parts will be subject to transfer restrictions, except in limited circumstances, until 30 days following the consummation
of the Business Combination, (ii) the Placement Warrants will be non-redeemable so long as they are held by the initial holder
thereof (or any of its permitted transferees), and will be exercisable on a “cashless” basis if held by any Subscriber
or its permitted transferees and will expire on the fifth anniversary following consummation of the Business Combination and (iii)
the Units and their component parts are being purchased pursuant to an exemption from the registration requirements of the Securities
Act and will become freely tradable only after they are registered or an exemption from registration is available, and the restrictions
described above in clause (i) has expired. Additionally, each Subscriber acknowledges and agrees that the Units and their component
parts and the related registration rights will be deemed compensation by the Financial Industry Regulatory Authority (“FINRA”)
and will therefore, pursuant to Rule 5110(g) of the FINRA Manual, be subject to lock-up for a period of 180 days immediately following
the date of effectiveness or commencement of sales in the IPO, subject to certain limited exceptions to permitted transferees
hereunder and in accordance with FINRA Rule 5110(g)(2). Additionally, the Units and their component parts and the related registration
rights may not be sold, transferred, assigned, pledged or hypothecated for a one-year period (including the foregoing 180 day
period) following the effective date of the Registration Statement except to any underwriter or selected dealer participating
in the IPO and the bona fide officers or partners of any Subscriber and any such participating underwriter or selected dealer. Additionally,
the Units and their component parts and the related registration rights will not be the subject of any hedging, short sale, derivative,
put or call transaction that would result in the economic disposition of such securities by any person for a period of 180 days
immediately following the date of effectiveness or commencement of sales in the IPO.

 

	 	9.	Governing
    Law; Jurisdiction; Waiver of Jury Trial.

 

This
Agreement shall be governed by and construed in accordance with the laws of the State of New York for agreements made and to be
wholly performed within such state without regard to conflicts. The parties hereto hereby waive any right to a jury trial in connection
with any litigation pursuant to this Agreement and the transactions contemplated hereby.

 

	 	10.	Assignment;
    Entire Agreement; Amendment.

 

10.1
Assignment. Neither this Agreement nor any rights hereunder may be assigned by any party to any other person other than by
any Subscriber to a person agreeing to be bound by the terms hereof, including the waiver contained in Section 7 hereof.

 

10.2
Entire Agreement. This Agreement sets forth the entire agreement and understanding between the parties as to the subject
matter thereof and merges and supersedes all prior discussions, agreements and understandings of any and every nature among them.

 

    	 	6	 

     

    

 

10.3
Amendment. Except as expressly provided in this Agreement, neither this Agreement nor any term hereof may be amended,
waived, discharged or terminated other than by a written instrument signed by the party against whom enforcement of any such amendment,
waiver, discharge or termination is sought.

 

10.4
Binding upon Successors. This Agreement shall be binding upon and inure to the benefit of the parties hereto and to their
respective heirs, legal representatives, successors and permitted assigns. 

 

	 	11.	Notices.

 

11.1
Notices. Unless otherwise provided herein, any notice or other communication to a party hereunder shall be sufficiently given
if in writing and personally delivered or sent by facsimile or other electronic transmission with copy sent in another manner
herein provided or sent by courier (which for all purposes of this Agreement shall include Federal Express or other recognized
overnight courier) or mailed to said party by certified mail, return receipt requested, at its address provided for herein or
such other address as either may designate for itself in such notice to the other.  Communications shall be deemed to
have been received when delivered personally, on the scheduled arrival date when sent by next day or 2nd-day courier service,
or if sent by facsimile upon receipt of confirmation of transmittal or, if sent by mail, then three days after deposit in the
mail. If given by electronic transmission, such notice shall be deemed to be delivered (a)  if by a posting on an electronic
network together with separate notice to the stockholder of such specific posting, upon the later of (1) such posting and
(2) the giving of such separate notice; and (b) if by any other form of electronic transmission, when directed to the
stockholder.

 

	 	12.	Counterparts.

 

This
Agreement may be executed in one or more counterparts, all of which when taken together shall be considered one and the same agreement
and shall become effective when counterparts have been signed by each party and delivered to the other party, it being understood
that both parties need not sign the same counterpart. In the event that any signature is delivered by facsimile transmission
or by e-mail delivery of a “pdf” format data file, such signature shall create a valid and binding obligation of the
party executing (or on whose behalf such signature is executed) with the same force and effect as if such facsimile or “.pdf”
signature page were an original thereof.

 

	 	13.	Survival;
    Severability.

 

13.1
Survival. The representations, warranties, covenants and agreements of the parties hereto shall survive the Closing.

 

13.2
Severability. In the event that any provision of this Agreement becomes or is declared by a court of competent jurisdiction
to be illegal, unenforceable or void, this Agreement shall continue in full force and effect without said provision; provided
that no such severability shall be effective if it materially changes the economic benefit of this Agreement to any party.

 

	 	14.	Headings.

 

The
titles and subtitles used in this Agreement are used for convenience only and are not to be considered in construing or interpreting
this Agreement.

 

	 	15.	Lock-Up.

 

15.1 Until 30 days
after the consummation of the Business Combination (“Unit Lock-Up Period”), Subscribers shall not, except as
described in the Registration Statement, (i) sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option
to purchase or otherwise dispose of or agree to dispose of, directly or indirectly, the Units, Placement Shares, Placement Rights,
Right Shares, Placement Warrants, or Warrant Shares.

 

15.2  Notwithstanding
the provisions contained in Section 15.1 hereof, any Subscriber or any of its Permitted Transferees (as defined below) may transfer
the Units, Placement Shares, Placement Rights, Right Shares, Placement Warrants or Warrant Shares: (1) in connection with the
Business Combination with the consent of the Company to any third party that agrees in writing to be bound by the provisions of
this agreement; and (2) (a) to the Company’s officers, the Company’s directors, the initial stockholders of the Company
(the “Initial Holders”) or such Subscriber’s officers, directors, equityholders (direct or indirect)
or other affiliates, (b) to an affiliate or immediate family member of any of the Company’s officers, directors or Initial
Holders, or such Subscriber’s officers, directors and direct and indirect equityholders, (c) to any member, officer or director
of an Initial Holder, or any immediate family member, partner, affiliate or employee of a member of an Initial Holder, (d) by
gift to any permitted transferee under any of the immediately preceding subsections (a) through (c), a trust, the beneficiaries
of which are one or more permitted transferee under any of the immediately preceding subsections (a) through (c), or a charitable
organization, (e) by virtue of laws of descent and distribution upon death of any of the Company’s officers, the Company’s
directors, the Initial Holders, members of an Initial Holder, or any officers, directors or direct or indirect equityholders of
such Subscriber, (f) pursuant to a qualified domestic relations order, (g) in the event of the Company’s liquidation prior
to consummation of the Business Combination or (h) by virtue of the laws of Delaware, or an Initial Holder’s limited liability
company agreement upon dissolution of such Initial Holder or the organizational documents of such Subscriber upon dissolution
of such Subscriber (each, a “Permitted Transferee”); provided, however, that these transferees enter into a
written agreement with the Company agreeing to be bound by the transfer restrictions set forth herein.

 

    	 	7	 

     

    

 

15.3
Each Subscriber agrees that after the Unit Lock-Up Period has elapsed, the Units, Placement Shares, Placement Rights, Right
Shares, Placement Warrants and Warrant Shares owned by such Subscriber shall only be transferable or saleable pursuant to a sale
registered under the Securities Act or pursuant to an available exemption from registration under the Securities Act. The Company
and the Subscribers each acknowledge that pursuant to that certain registration rights agreement to be entered into among the
Company, the Subscribers, the Initial Holders and the other parties thereto, the parties thereto may request that a registration
statement relating to the Units, Placement Shares, Placement Rights, Right Shares, Placement Warrants or Warrant Shares be filed
by the Company with the SEC prior to the end of the Unit Lock-Up Period; provided, however, that such registration statement does
not become effective prior to the end of the Unit Lock-Up Period.

 

15.4 Subject
to the limitations described herein, each Subscriber shall retain all of such Subscriber’s rights as a security holder with
respect to the Units, Placement Shares, Placement Rights, Right Shares, Placement Warrants and Warrant Shares during the Unit
Lock-Up Period including, without limitation, the right to vote Placement Shares.

 

15.5 During
the Unit Lock-Up Period, all dividends payable in cash with respect to such securities shall be paid, as applicable, to each security
holder, but all dividends payable in Common Stock or other non-cash property shall become subject to the applicable lock-up period
as described herein and shall only be released from such lock-up in accordance with the provisions of this Section 15.

 

[remainder
of page intentionally left blank]

 

 

    	 	8	 

     

    

 

This
subscription is accepted by the Company on the [__] day of June 2018.

 

	 	ALLEGRO
    MERGER CORP.
	 	 	 
	 	By:	 
	 	 	Name:  
	 	 	Title:
       

 

Accepted
and agreed on the date hereof

 

	 	SUBSCRIBERS:

         

        CANTOR
        FITZGERALD & CO.

	 	 	 
	 	By:	 
	 	 	Name:  
	 	 	Title:    

 

	 	CHARDAN
    CAPITAL MARKETS, LLC
	 	 	 
	 	By:	 
	 	 	Name:  
	 	 	Title:    

   

 

 

[Placement
Unit Subscription Agreement – Underwriters]

 

     

     

    

 

SCHEDULE
A

 

	NAME OF SUBSCRIBER	 	NUMBER OF UNITS	 
	Cantor Fitzgerald & Co.	 	 	38,750	 
	Chardan Capital Markets, LLC	 	 	11,250

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