<PAGE>   1

                                                                   EXHIBIT 10.12

                           ELEVENTH AMENDMENT TO LEASE

         THIS AGREEMENT made this 20th day of April, 2000 by and between KGE
Associates, L.P., a partnership hereinafter referred to as "Landlord" and
Telemate.Net Software, Inc., a Georgia Corporation hereinafter referred to as
"Tenant".

         WHEREAS, the parties hereto made and entered into a lease agreement
dated January 28, 1992 and amended on June 11, 1993, June 22, 1994, March 30,
1995, June 14, 1996, July 26, 1996, August 2, 1996, July 16, 1998, November, 9,
1999, November 10, 1999 and November 15, 1999 for certain premises (hereinafter
referred to as the "Premises") situated at Perimeter Crest Office Park, 4250
Perimeter Park Drive, Suite 200, Atlanta, Georgia 30341.

         NOW, THEREFORE, in consideration of the mutual promises given one to
the other, the parties hereto intending to be legally bound, do hereby covenant
and agree as follows:

         PREMISES.

         The Premises currently being leased by Tenant under the Lease is 52,848
         square feet. With this expansion the space being leased by Tenant will
         be 56,173.

         1)       EXPANSION SPACE

         a.       The Premises shall be expanded to include an additional 3,325
         square feet, as shown in yellow on Exhibit "B" attached and made a part
         hereto ("Expansion Premises") located at 4250 Perimeter Park South,
         Suites 102 and 109, Atlanta, Georgia 30341. Commencement Date" means
         the later of (1) Landlord's delivery of possession of the Expansion
         Premises to Tenant, or (ii) July 1, 2000. If by the Commencement Date
         Landlord has not substantially completed the improvements to the
         Expansion Premises required to be made hereof or if Landlord, for any
         reason whatsoever cannot deliver possession of the Expansion Premises
         to Tenant by the Commencement Date, then the Commencement Date shall be
         postponed (and rent herein provided, pro-rata to the Expansion
         Premises, shall not commence) until the earlier of either (I) the date
         of actual occupancy of the Expansion Premises by Tenant or (ii) the
         date immediately following the day Landlord has achieved substantial
         completion of such improvements.

         b.       If, and to the extent, Landlord's substantial completion of
         the improvements to Expansion Premises pursuant to Exhibit "A" attached
         hereto is delayed due to any act or omission of Tenant or anyone acting
         under or for Tenant (any such delay being hereinafter referred to as
         "Tenant's Delay"), then the Commencement Date shall be the date
         specified above, subject to adjustment as provided therein, but without
         extension as result of Tenant's Delay; provided that from the
         Commencement Date, as so determined, until the earlier of (I) the date
         of actual occupancy of the Expansion Premises by Tenant or (ii) the
         date immediately following the date Landlord should have achieved
         substantial completion of such improvements but for Tenant's Delay,
         Tenant's obligations under this Lease shall be to the payment of any
         and all Rent due hereunder.

         c.       Within five (5) days of written request by Landlord, Tenant
         agrees to execute and deliver to Landlord a Letter Agreement As To Term
         and Premises pursuant to Exhibit "B" attached and made a part hereof,
         setting forth the exact Commencement


<PAGE>   2

         Date of the Expansion and stating that all tenant improvements to be
         constructed by Landlord have been substantially completed, subject to
         any outstanding punch-list items.

         2)       ALTERATIONS AND IMPROVEMENTS

         a.       Landlord will make available a Tenant Improvements Allowance
         ("Landlord's Tenant Improvement Allowance") of $14.00 per square foot
         of Expansion Space. Included as part of the Tenant Improvement
         Allowance shall be a construction management fee in the amount of five
         percent (5%) of the actual improvement cost, and all costs associated
         with architectural & mechanical drawings. The design and construction
         of the Tenant Improvements shall be in accordance with working drawings
         to be approved by Landlord and Tenant prior to commencement of
         construction. The Premises will be prepared in accordance with Exhibit
         "A" attached hereto and by this reference made a part hereof
         ("Landlord's Construction"). Landlord shall have such work performed
         promptly, diligently and in a good and workmanlike manner. The
         aforementioned Tenant Improvement Allowance shall be utilized by the
         earlier of 1) June 30, 2001 or 2) 90 days from the day Building 4250,
         Suite 119, which is presently occupied by Heritage Property Management
         becomes vacant. Should Tenant fail to utilize the Tenant Improvement
         Allowance by June 30, 2001 then this obligation of the Landlord shall
         be null and void and of no further force or effect. Landlord agrees and
         acknowledges to allow Tenant to utilize any excess Tenant Improvement
         Allowance within the existing premises or within other premises
         occupied by Tenant for improvements to the Premises. Tenant
         acknowledges and agrees that any such work to be performed pursuant to
         the herein defined excess Tenant Improvement Allowance, shall be
         subject to Landlord's reasonable approval and in the event Tenant does
         not utilize the excess Tenant Improvement Allowance prior to December
         31, 2001; this obligation of the Landlord shall be null and void and of
         no further force or effect.

         b.       Upon substantial completion of Landlord's Construction, Tenant
         shall inspect the Premises and identify "punch-list" items for Tenant's
         final acceptance. "Substantial Completion" means the Premise is
         reasonably satisfactory for acceptance and in accordance with the work
         depicted on Exhibit "A".

         c.       Tenant may request substitutions, additional or extra work
         and/or materials over and above that required as depicted and described
         on Exhibit "A" hereof and/or under Tenant's approved Plans to be
         performed by Landlord, provided that the Extra Work, at Landlord's
         option, (I) shall not require the uses of contractors or types of
         contractors other than those normally engaged by Landlord in the
         Building; (ii) shall not delay completion of Landlord's Construction or
         the Commencement Date; (iii) shall be practicable and consistent with
         existing physical conditions in the Building and with plans for the
         Building which have been filed with the applicable governmental
         authorities having jurisdiction thereover; (iv) shall not impair
         Landlord's ability to perform any of Landlord's obligations hereunder
         or under this Lease or any other Agreement with respect to space in the
         Building; (v) shall not affect any portion of the Building other than
         the Premises; and (vi) any such work requested by Tenant and approved
         by Landlord, shall not cause Landlord's Construction to exceed the
         Tenant Improvement Allowance provided for herein. All Extra Work shall
         require the installation of new materials and shall be otherwise
         subject to Landlord's reasonable approval.


<PAGE>   3

         3)       TERM

         This Eighth Lease Amendment shall commence on the Commencement Date as
         defined herein and terminate September 30, 2003.

         4)       BASE RENTAL

         Tenant agrees to pay base rental for the Premises in accordance with
         the base rental schedules, and during the term, as defined in the Sixth
         Amendment to Lease, Seventh Amendment to Lease, Eighth Amendment to
         Lease, Ninth Amendment to Lease, Tenth Amendment to Lease and this
         Eleventh Amendment to Lease, Tenant agrees to pay base rental for the
         Expansion Premises (5,962 square feet) to Landlord during the term as
         defined in this Eighth Amendment To Lease, payable on or before the
         first day of each and every month, in advance, in accordance with the
         following schedule:

<TABLE>
<CAPTION>
         Payment Periods      Monthly Rent      Annual Base Rent   Base Rent/SF
         ---------------      ------------      ----------------   ------------

         <S>                  <C>               <C>                <C>
         7/1/00-6/30/01         $3,485.71           $41,828.50        $12.58
         7/1/01-6/30/02         $3,607.63           $43,291.50        $13.02
         7/1/02-6/30/03         $3,735.08           $44,821.00        $13.48
         7/1/03-09/30/03        $3,865.31           $46,383.75        $13.95
</TABLE>

All other terms, provisions and covenants of the Lease Agreement dated January
28, 1992, as further amended, shall remain in full force and effect.

                         (Signatures on following page)


<PAGE>   4

         IN WITNESS WHEREOF, the parties herein have hereto set their hands and
seals, in duplicate, the day and year first above written.

                                    "LANDLORD"

                                    KGE ASSOCIATES, L.P.


                                    By:      /s/ Elizabeth Hawkins
                                       -----------------------------------------


                                    Its:
                                        ----------------------------------------

                                    Date:             5/25/01
                                         ---------------------------------------

                                    "TENANT"

                                    TELEMATE.NET SOFTWARE, INC.


                                    By:      /s/  Janet Van Pelt
                                       -----------------------------------------


                                    Its:     CFO
                                        ----------------------------------------

                                    Date:    5/24/01
                                         ---------------------------------------


<PAGE>   5

                                   EXHIBIT "A"

                             LANDLORD'S CONSTRUCTION

TENANT'S PLANS AND SPECIFICATIONS.

Landlord and Tenant, at Landlord's sole cost and expense, subject to provisions
of Paragraph 6 hereof, shall cause to be prepared by Landlord's architect and/or
designer and/or engineer the following:

         (a)      Complete, finished, detailed construction documents and
specifications for Tenant's partition layout, ceiling and other installations
for the work to be done by Landlord under Paragraph 6 hereof, subject to
limitations therein, which shall be prepared by Landlord's architect and/or
designer.

         (b)      Complete mechanical and electrical plans and specifications
where necessary for the installation of air conditioning system and ductwork,
heating, electrical, plumping and other engineering plans for the work to be
done by Landlord under Paragraph 6 hereof, subject to limitations therein, which
shall be prepared by Landlord's architect and/or designer and/or engineer.

         (c)      Any subsequent modifications to the construction documents and
specifications requested by Tenant.

All such plans and specifications are expressly subject to Landlord's approval
and shall comply with all applicable laws, rules, regulations and conditions of
Paragraph 6 hereof. Tenant's Plans shall be delivered to Tenant for Landlord's
approval on or before ________________ (subject to written modification between
the parties). Such approval shall not be unreasonably withheld. If Tenant shall
have reasonable grounds for withholding its approval of Tenant's Plans, Tenant,
within three (3) business days of receipt of Tenant's Plans, shall provide
Landlord with written notice of its disapproval detailing with specificity those
aspects of Tenant's Plans which Tenant disapproves. In the event Tenant fails to
provide Landlord with written notice within such three (3) business day period,
Tenant shall conclusively be deemed to have approved Tenant's Plans. In the
event Tenant provides timely written notice of its disapproval of Tenant's
Plans, within such three (3) business day period, Landlord shall amend Tenant's
Plans accordingly and deliver the amended plans to Tenant for approval. The same
procedures as for the original Tenant's Plans shall be applicable to any
amendments of Tenant's Plans under the preceding sentences. If Tenant shall fail
to approve Tenant's Plans within the times provided in this paragraph, then and
in addition to any other rights or remedies of Landlord, at Landlord's option,
may terminate this Lease Agreement and/or accelerate by the number of days of
such delay the Commencement Date. In addition, Tenant shall reimburse Landlord
for any and all expenses, losses, costs and damages suffered by Landlord and
caused by such delay. Such option shall not be exercised until at least fifteen
(15) days after the default in question.

         2.       Without the prior written consent of Landlord, Tenant shall
make no changes in Tenant's Plans after approval thereof.

         3.       After approval of Tenant's Plans, Landlord shall obtain from
its general contractor and submit to Tenant a quotation of the cost of
improvements of the Premises in

<PAGE>   6

accordance with Tenant's Plans. Upon written approval of such quotation by
Tenant, Landlord and Tenant shall be deemed to have given final approval to
Tenant's Plans, including but not limited to a date for completion of the work
required thereunder, and Landlord shall be authorized to proceed with the
improvements of the Premises in accordance with Tenant's Plans. Failure of
Tenant to reasonably approve any such quotation shall abate Landlord's
obligation to proceed with any improvements of the Premises, but shall not
postpone the Commencement Date by more than seven (7) days.

Tenant's Plans and a quotation of the cost of Tenant's extra work (as
hereinafter defined) shall be finally approved by Tenant and Landlord as
provided herein no later than __________________. A copy of Tenant's Plans as so
finally approved shall be signed and dated by both Tenant and Landlord and
delivered to Landlord for its records. A copy of the construction contract for
the improvements of the Premises in accordance with approved Tenant's Plans
shall be initialed and dated by both Tenant and Landlord and attached to this
Lease as an additional exhibit hereto.

LANDLORD'S CONSTRUCTION

Landlord agrees, subject to limitations of Paragraph 6 hereof, at Landlord's
sole cost and expense and in conformance with Construction Documents to provide
and install the Tenant Improvements substantially in accordance with Tenant's
Plans as approved by Landlord and Tenant.

EXTRA WORK

Tenant may request substitutions, additional or extra work and/or materials over
and above that required in Paragraph 2(a) hereof and/or under Tenant's Plans
approved above (herein called "Extra Work") to be performed by Landlord,
provided that the Extra Work, at Landlord's option, (i) shall not require the
use of contractors or types of contractors other than those normally engaged by
Landlord in the Building; (ii) shall not delay completion of Landlord's
Construction or the Commencement Date; (iii) shall be practicable and consistent
with existing physical conditions in the Building and with plans for the
Building which have been filed with the applicable governmental authorities
having jurisdiction thereover; (iv) shall not impair Landlord's ability to
perform any of Landlord's obligations hereunder or under this Lease or any other
Agreement with respect to space in the Building; and (v) shall not affect any
portion of the Building other than the Premises. All Extra Work shall require
the installation of new materials and shall be otherwise subject to Landlord's
reasonable approval.

         2.       Subject to Landlord's written consent, Tenant may request the
omission of an item of work required under the approved Tenant's Plans, provided
that such omission shall not delay the completion of the Premises, and Landlord
thereafter shall not be obligated to install same. No credit shall be granted to
Tenant for such omitted items.

PAYMENTS

As costs are incurred and bills are received by Landlord in the performance of
Extra Work, Tenant shall make periodic payments to Landlord within ten (10) days
after receipt by Tenant of a statement therefore from Landlord.

COOPERATION


<PAGE>   7

All work not within the scope of the normal construction trades employed for the
Building, such as the furnishing and installing of draperies, furniture,
telephone equipment and wiring, alarm systems, and office equipment, shall be
furnished and installed by Tenant at Tenant's expense. Tenant shall adopt a
schedule in conformance with the schedule of Landlord's contractors and shall
conduct its work in such a manner as to maintain harmonious relations and as not
to interfere unreasonably with or delay the work of Landlord's contractors.
Tenant shall cause its telephone and alarm contractors to contact Landlord with
regard to installation of a telephone system in the Premises within three (3)
business days of the date Landlord commences construction of the Premises.

<PAGE>   8

                                   EXHIBIT "C"

KGE Associates, LP ("Landlord") and Telemate.Net Software, Inc., a Georgia
corporation ("Tenant"), do each hereby agree and certify to the other that the
Term of that certain Eleventh Amendment to Lease between Landlord and Tenant
dated April 20, 2000, ("Lease") commenced on the day of May 25, 2000,
and will expire on the 30th day of September, 2003, unless extended or sooner
terminated as may be provided in the Lease. Tenant hereby acknowledges that it
has accepted delivery of the Phase I Premises, containing 3,325 rentable square
feet, in "substantially complete" condition as defined in the Lease, and that
said Premises are in full compliance with all requirements of the Lease, except
for defects of which Tenant gives Landlord notice with reasonable specificity
within ten (10) business days from the Commencement Date referenced above.

IN WITNESS WHEREOF, the parties have caused their duly authorized
representatives to execute this instrument under seal as of the 25 day of May,
2000.

ATTEST:                                     LANDLORD: KGE ASSOCIATES, LP


                                            By:     /s/ Elizabeth B. Hawkins
-------------------------                       --------------------------------

                                            Title: Secretary of General Partner
                                                  ------------------------------

                                            Its:
                                                --------------------------------

                                            Date:           5/25/00
                                                 -------------------------------

ATTEST:                                     TENANT:  TELEMATE.NET SOFTWARE, INC.


                                            By:     /s/ Janet Van Pelt
-------------------------                       --------------------------------

                                            Title:           CFO
                                                  ------------------------------

                                            Date:           5/25/00
                                                 -------------------------------
                                                      (Corporate Seal)