<PAGE>

                                                                    EXHIBIT 10.8

                              SUBLEASE AGREEMENT
                              ------------------


     This Sublease Agreement (this "Sublease") is made this 31/st/ day of
                                                           ------
January, 2001 between National Data Corporation, a Delaware corporation
-------
("Sublandlord"), and National Data Payment Systems, Inc., a New York corporation
                                                            --------------------
("Subtenant").


                                R E C I T A L S
                                - - - - - - - -

     Seville Plaza Management Corporation ("Landlord"), as landlord, and
Sublandlord, successor in interest to Spring Anesthesia Group, Inc., as tenant,
are parties to that certain Koll Office Lease dated June 3, 1993, for the lease
of certain space located in Seville Plaza, 5473 Kearny Villa Road, San Diego,
California (the "Building"), said lease having been amended by Amendment to
Office Lease dated March 18, 1998 (as so amended the "Lease"; all capitalized
terms used herein and not otherwise defined shall have the meanings ascribed
thereto in the Lease).

     Sublandlord and Subtenant desire to enter into this Sublease, pursuant to
the terms of which Subtenant will lease from Sublandlord and Sublandlord will
lease to Subtenant a portion of the Premises.

     NOW, THEREFORE, for and in consideration of Ten and No/100 Dollars ($10.00)
and the mutual covenants and obligations set forth in this Sublease, Sublandlord
and Subtenant do hereby agree as follows:

     1.   Subleased Premises.  Sublandlord does hereby lease to Subtenant, and
          ------------------
Subtenant leases and rents from Sublandlord, that portion of the Premises
consisting of approximately 2,274 rentable square feet (2,274 rentable square
feet being the agreed upon, conclusive square footage of the Subleased Premises
for purposed hereof) as shown outlined and cross-hatched on the floor plan
attached hereto as Exhibit A and incorporated herein by this referenced (the
                   ---------
"Subleased Premises"), said Subleased Premises being Suite 110.  The Subleased
Premises are being leased by Sublandlord to Subtenant "AS IS" and Sublandlord
shall not be obligated to construct any demising walls or make any improvements
or alterations whatsoever with regard to the Subleased Premises.  Subtenant
shall not make any improvements or alterations to the Subleased Premises without
Sublandlord's prior written consent.

     2.   Term.  The term of this Sublease ("Sublease Term") shall begin on the
          ----
1/st/ day of February, 2001 and shall expire at 12:00 midnight on the expiration
-----        --------
date of the Lease unless the Lease or this Sublease is sooner terminated in
accordance with the terms and conditions set forth therein or herein.
<PAGE>

     3.   Rent.  Commencing on the Commencement Date and continuing through and
          ----
including March 31, 2001 (the "First Rent Period"), Subtenant shall pay to
Sublandlord a base rent ("Base Rent") of Nineteen and 50/100 Dollars ($19.50)
per rentable square foot of the Subleased Premises per annum ($44,343.00).  The
Base Rent during the First Rent Period shall be payable by Subtenant to
Sublandlord in advance in monthly installments of Three Thousand Six Hundred
Ninety-Five and 25/100 Dollars ($3,695.25) each, which are due and payable on or
before the first day of each calendar month during the First Rent Period with
appropriate prorations for partial months.  Commencing on April 1, 2001 and
continuing through and including the remainder of the Sublease Term (the "Second
Rent Period"), Subtenant shall pay to Sublandlord a Base Rent of Twenty and
46/100 Dollars ($20.46) per rentable square foot of the Subleased Premises per
annum ($46,526.04).  The Base Rent during such period shall be payable by
Subtenant to Sublandlord in advance in monthly installments of Three Thousand
Eight Hundred Seventy-Seven and 17/100 Dollars ($3,877.17) each, which are due
and payable on or before the first day of each calendar month during the Second
Rent Period with appropriate prorations for partial months.  Throughout the
Sublease Term, Subtenant shall also pay as additional rent hereunder
("Additional Rent") (i) Subtenant's pro rata share (based on the rentable square
footage of the Subleased Premises compared to the rentable square footage of the
Premises) of (a) all Operating Expenses, and (b) costs for outside vendors and
service providers engaged by Sublandlord to provide janitorial, security or
other services to the Premises as a whole, and (ii) any amounts due under the
Lease for separate or other charges (such as excess electrical, overtime HVAC,
damage expenses, etc.) and incurred at Subtenant's request or otherwise
allocable or attributable to the Subleased Premises.  All Additional Rent shall
be payable by Subtenant to Sublandlord at the time and in the same manner such
payments are due by Sublandlord under the Lease, or as otherwise reasonably
required by Sublandlord from time to time.  Base Rent and Additional Rent are
referred to collectively in this Sublease as "Rent".  Subtenant shall also pay
all tax due with regard to the Rent pursuant to the laws of the State of
California.

     4.   Relationship to Lease.  This Sublease and all of Subtenant's rights
          ---------------------
hereunder are expressly subject to and subordinate to all of the terms of the
Lease.  Subtenant hereby acknowledges that it has received copies of the Lease
and has read all of the terms and conditions thereof.  Subtenant hereby agrees
to assume all obligations of Sublandlord, as "Tenant" under the Lease, with
respect to the Subleased Premises.  All of the terms and conditions of the Lease
are hereby incorporated into this Sublease by reference as if fully set forth
herein and except that "Landlord" shall be read as "Sublandlord" and "Tenant"
shall be read as "Subtenant"; provided, however, that (i) Subtenant hereby
acknowledges that Subtenant shall look solely to Landlord for the performance of
all the Landlord's obligations under the Lease and that Sublandlord shall not be
obligated to provide any services to Subtenant or otherwise perform any
obligations in connection with this Sublease, and (ii) Subtenant shall not be
entitled to exercise (or to require Sublandlord to exercise) any right of first
offer, right of first refusal, right to contest taxes, renewal option, purchase
option, termination option, contraction option, expansion option or any such
other right or option granted to Sublandlord as "Tenant" under the Lease.
Subtenant

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<PAGE>

acknowledges that any termination of the Lease will result in a termination of
the Sublease.

    5.   Use.  Subtenant's use of the Subleased Premises shall be strictly in
         ---
accordance with the use provisions of the Lease.

    6.   Default.  Any act or omission by Subtenant that would constitute a
         -------
default under the Lease shall, subject to the same notice and cure provisions
provided in the Lease, be deemed a default by Subtenant under this Sublease.  In
addition, any failure by Subtenant to pay Rent when due (and the continuance of
such failure for five (5) days following notice from Sublandlord to Subtenant)
or any failure by Subtenant to perform any other obligations required under this
Sublease, shall be deemed a default hereunder.  Any such default by Subtenant
shall entitle Sublandlord to exercise any and all remedies available to Landlord
under the Lease or any other remedies available at law or in equity under the
laws of the State of California.

    7.   Quiet Enjoyment.  Provided Subtenant has performed its obligations
         ---------------
hereunder, Subtenant shall have the quiet enjoyment of the Subleased Premises
without interference by Sublandlord or anyone claiming by, through or under
Sublandlord.  Sublandlord shall comply with its obligations under the Lease.
Sublandlord will use reasonable efforts to enforce Landlord's obligations under
the Lease, but if Sublandlord chooses not to pursue an action to enforce any of
Landlord's obligations but Sublandlord desires to enforce such obligations,
Sublandlord will assign its rights to Subtenant and will cooperate with
Subtenant's efforts to enforce such obligations so long as such enforcement
efforts are at Subtenant's sole expense and Subtenant indemnifies Sublandlord
from any damages, claims or expenses resulting from such enforcement effort or
Sublandlord's cooperation therewith.

    8.   Insurance and Indemnities.  Subtenant hereby agrees to indemnify and
         -------------------------
hold Landlord and Sublandlord harmless, with regard to its leasing and use of
Subleased Premises, to the same extent that Tenant is required to indemnify and
hold Landlord harmless with respect to the Premises.  Likewise, Subtenant hereby
agrees to obtain and provide evidence satisfactory to Sublandlord, on or before
the date of this Sublease, that Subtenant is carrying insurance in the same
amounts and of the same types (including any required waiver of subrogation
provisions or endorsements) required to be carried by Sublandlord, as "Tenant"
under the Lease, with regard to the Premises.

    9.   Subleasing and Assignment.  Subtenant shall have no further right to
         -------------------------
sublease or assign its rights under this Sublease or its rights with regard to
the Subleased Premises without the prior written consent of Sublandlord, which
consent may be withheld in Sublandlord's sole discretion.  Notwithstanding the
foregoing, Subtenant may assign or sublet its rights and obligations under this
Sublease without Sublandlord's prior consent to a successor corporation into
which or with which Subtenant is merged or consolidated or which acquired all or
substantially all of Subtenant's assets and property,

                                       3
<PAGE>

provided that such successor corporation assumes substantially all of the
obligations and liabilities of Subtenant hereunder.

    10.  Condition of Subleased Premises.  Upon the expiration or earlier
         -------------------------------
termination of this Sublease, Subtenant shall return the Subleased Premises to
Sublandlord in the condition required by the Lease, normal wear and tear and
damage by casualty or condemnation excepted.

    11.  Notices.  Notices by Sublandlord and Subtenant shall be given to each
         -------
other in the same manner provided by the Lease:

          Subtenant:                         National Data Payment Systems, Inc.
                                             c/o Global Payment Inc.
                                             One National Data Plaza
                                             Atlanta, Georgia 30329
                                             Attention:  Real Estate Department


          With a copy to:                    National Data Payment Systems, Inc.
                                             c/o Global Payment Inc.
                                             One National Data Plaza
                                             Atlanta, Georgia 30329
                                             Attention:  General Counsel

          Sublandlord:                       National Data Corporation
                                             Two National Data Plaza
                                             Atlanta, Georgia 30329
                                             Attention:  Real Estate Department

          With a copy to:                    National Data Corporation
                                             Two National Data Plaza
                                             Atlanta, Georgia 30329
                                             Attention:  General Counsel

    12.  Signs.  Subtenant shall have no right whatsoever to install any signs
         -----
in the Premises or the Building without the prior written consent of
Sublandlord, which may be granted or withheld by Sublandlord in its sole
discretion.

    13.  Miscellaneous.  This Sublease shall be governed by the laws of the
         -------------
State of California.  Time shall be of the essence with regard to the
obligations under this Sublease.  This Sublease supersedes all prior discussions
and agreements between the parties and incorporates their entire Agreement.

                                       4
<PAGE>

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



                                  SUBLANDLORD:

                                  National Data Corporation

                                  By: /s/ Randolph L. M. Hutto
                                      ---------------------------
                                   Name: Randolph L. M. Hutto
                                         ------------------------
                                   Title: Chief Financial Officer
                                          -----------------------


                      [Signatures continued on next page]

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<PAGE>

                                  SUBTENANT:

                                  National Data Payment Systems, Inc.

                                  By: /s/ Paul R. Garcia
                                      --------------------------
                                  Name: Paul R. Garcia
                                        ------------------------
                                  Title: Chief Executive Officer
                                        ------------------------

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<PAGE>

                               Landlord Consent
                               ----------------

     The undersigned, as Landlord under the Lease, does hereby consent to the
within Sublease.  Landlord does further agree to provide to Subtenant any notice
of default by Sublandlord, as "Tenant" under the Lease, such notice to be
delivered simultaneously with the notice provided to Sublandlord.

                                  Seville Plaza Management
                                  Corporation

                                  By: ___________________________
                                   Name: ________________________
                                   Title: _______________________

                                             [CORPORATE SEAL]

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<PAGE>

                                                                       EXHIBIT A


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