<PAGE>   1
                                                                  EXHIBIT 10.15


                           EIGHTH AMENDMENT TO LEASE


         THIS AGREEMENT made this 9th day of November, 1999 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 and July 16, 1998, 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:

1.       PREMISES.

         The Premises currently being leased by Tenant under the Lease is
         33,356 square feet. With this expansion the space being leased by
         Tenant will be 39,844.

2.       EXPANSION SPACE

         a.       The Premises shall be expanded to include an additional 6,488
         square feet ("Expansion Premises") located at 4200 Perimeter Park
         South, Suite 103, Atlanta, Georgia 30341. Commencement Date" means the
         earlier of (1) Landlord's delivery of possession of the Expansion
         Premises to Tenant, or (ii) January 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 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.

3.       ALTERATIONS AND IMPROVEMENTS

         a.       Landlord will make available a Tenant Improvements Allowance
         ("Landlord's Tenant Improvement Allowance") of $6.00 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. In the
         event the cost to make the necessary improvements exceeds the Tenant
         Improvement Allowance above the Landlord agrees to amortize the excess
         amount over the term of the lease with Tenant repaying the


<PAGE>   2


         overage amount in equal monthly installments over the term of this
         Agreement. Amortization shall be at an interest rate of 10% per annum.

         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.

4.       TERM

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

5.       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 and for this Ninth Amendment, Tenant agrees to pay base
         rental for the Expansion Premises (6,440 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>
         12/1/99-11/30/00        $7,028.67                 $84,344.00                 $13.00
         12/1/00-11/30/01        $7,274.67                 $87,296.04                 $13.46
         12/1/01-11/30/02        $7,531.49                 $90,377.84                 $13.93
         12/1/02-09/30/03        $7,791.01                 $93,492.08                 $14.41
</TABLE>

6.       NAME CHANGE

         Landlord & Tenant agree that beginning with the execution of this
         Eighth Amendment to Lease Tenant has legally changed its name to
         Telemate.Net Software, Inc.

7.       EXPANSION

         Tenant has no expansion rights under this Eighth Amendment to Lease

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 the following page)


<PAGE>   3


         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 B. Hawkins
                                    -------------------------------------------

                                 Its: Secretary of G.P.
                                     ------------------------------------------

                                 Date: 12/02/99
                                      -----------------------------------------


                                 "TENANT"

                                 TELEMATE.NET SOFTWARE, INC,

                                 By: /s/ Richard J. Post
                                    -------------------------------------------

                                 Its: Chief Financial Officer
                                     ------------------------------------------

                                 Date: 12/2/99
                                      -----------------------------------------


<PAGE>   4

                                                                     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 Tenant's
approval on or before December 10, 1999 (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 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 December 15, 1999. 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.


<PAGE>   5


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 6 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

Any costs associated with the aforementioned improvements which exceeds the
Tenant Improvement Allowance of $6.00 per square foot shall be amortized with a
10% interest rate over the remaining term of this Eight Amendment, payable in
equal monthly installments.

COOPERATION

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>   6

                                                                     EXHIBIT "B"


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 Eighth Amendment to Lease between Landlord and Tenant dated
November 9, 1999, ("Lease") commenced on the 1st day of February 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 Premises, containing 6,488 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.

Tenant agrees to pay an additional $.74 per square foot for the term of this
agreement for the amortization of tenant improvements over the Tenant
Improvement Allowance.

IN WITNESS WHEREOF, the parties have caused their duly authorized
representatives to execute this instrument under seal as of the 1st day of
February, 1999.



ATTEST:                             LANDLORD:   KGE ASSOCIATES, LP


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

                                    Title: Secretary of G.P.
                                          -------------------------------------

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

                                    Date: 02/01/00
                                         --------------------------------------



ATTEST:                             TENANT:  TELEMATE.NET SOFTWARE, INC.


/s/                                 By: /s/ Richard J. Post
---------------------------------      ----------------------------------------

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

                                    Date: 3/2/00
                                         --------------------------------------

                                                 (Corporate Seal)
<PAGE>   7

                                 EXHIBIT "B"
                                   PHASE I

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 Tenth Amendment to Lease between Landlord and Tenant dated
November 15, 1999, ("Lease") commenced on the 1st day of February, 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 3,570 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 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 1st day of
February, 2000.


ATTEST                                 LANDLORD: KGE Associates, LP
/s/
------------------------               By:  ELIZABETH B. HAWKINS
                                           -------------------------------------

                                       Title: Secretary of G.P.
                                              ----------------------------------

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

                                       Date:  02/01/00
                                             -----------------------------------


ATTEST                                 TENANT: Telemate.Net Software, Inc.
/s/
------------------------               By:  RICHARD J. POST
                                           -------------------------------------

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

                                       Date:  03/02/00
                                             -----------------------------------

                                                      (Corporate Seal)