General Information

The GAMS system and all connected solvers can be downloaded from the GAMS website at The use of the software is governed by the GAMS End User License Agreement, which is available on our website and can also be found in the GAMS System directory (eula.pdf). Without a valid GAMS license the system will not run and produces the following output:

*** No license specified and no gamslice.txt found in standard locations.

You can request a free demo license at The demo license lets you generate and solve linear models (LP, RMIP, and MIP) that do not exceed 2000 variables and 2000 constraints. For all other model types the model cannot be larger than 1000 variables and 1000 constraints. Some solvers might enforce additional limits for the demo license. The demo license of MIRO connector allows up to 10 indexed input and output symbols.

GAMS will terminate with an error message, if it hits one of the limits above:

*** Status: Terminated due to a licensing error
***         Inspect listing file for more information

The demo license is time-limited for 12 months and on expiration you need to request a new license. Moreover, a valid free demo license requires a recent GAMS version (not older than 18 months).

GAMS Community License

Users can request a free community license from The community license lets you generate and solve linear models (LP, MIP, and RMIP) that do not exceed 5000 variables and 5000 constraints. For all other model types the model cannot be larger than 2500 variables and 2500 constraints. Restrictions you experience with the demo license, i.e. additional limits enforced by some solvers, time-limitation of 12 months, and a recent GAMS system also apply to the community license. The free demo and community license cannot be combined with a professional license. These free demo and community licenses are for demonstration and evaluation but not for commercial and production work.

GAMS Licenses

GAMS licenses beyond the free demo and community license require a license for the GAMS Base Module and for most of the GAMS/Solvers and the GAMS/Solver-Links:

  • The GAMS Base Module includes the GAMS Language Compiler, GAMS-APIs, many utilities, some solvers without size restrictions, and most solvers in "demo" mode with a model size limitation. See details below.
  • A GAMS/Solver connects the GAMS Base module to a particular solver and includes a license for this solver to be used through GAMS. It is not necessary to install additional software. A GAMS/Solver-Link connects the GAMS Base Module to a particular solver, but does not include a license for the solver. It may be necessary to install additional software before the solver can be used.

We distinguish between academic and commercial licenses. Academic licenses can only be used for teaching and research at degree granting institutions. Moreover, we distinguish between time-limited and perpetual licenses. For perpetual licenses the first year of maintenance, support and updates is included in the initial purchase of the software. Maintained licenses qualify for free updates, adding components, platform-switching without additional charge, and multi-copy discounts on the same platform. After the first year maintenance can be extended by paying a fee. Licenses are typically limited to a single computer platform type (e.g. Windows or Linux), but there are also licenses available, which will work on all major platform supported by GAMS. Free academic licenses are available for certain solvers. Please visit the GAMS website for further information about the pricing of an appropriate license.

Installing or updating a license file

A GAMS license file is an ASCII file of six lines, which was sent to you via e-mail. Please copy all six lines into a file gamslice.txt and place this into a location searched by GAMS. Details can be found in the installation notes of the specific operating system:

Before installing a new GAMS version, please check whether it will work with your current GAMS license. The utility CHK4UPD can be used to see if a newer GAMS version is available and what the newest version is that can be used with a given license. This is done by running CHK4UPD without arguments or by giving the name of a local license file. CHK4UPD is also available through GAMS Studio and can be accessed through: Help -> Check for Update. Below is a sample output for a license, which is still under maintenance:

*** Processing GAMS system directory C:\gams\win64\24.8
*** Reading license file C:\ProgramData\GAMS\gamslice.txt
*** Your system is up to date

If your license is no longer under maintenance, you will receive a message like the one below:

*** Processing GAMS system directory C:\GAMS\win64\23.9
*** Reading license file C:\ProgramData\GAMS\gamslice.txt
*** Your license is 1276 days too old to run with the most recent system
*** The version of your GAMS system is 23.9.5
*** The last GAMS version you can use is 24.1.3
*** Please request the download of an older version from
*** For ordering an update to use the most recent version (24.8.5)
*** please contact your distributor

License Problems

Errors or warnings triggered by a problem with the GAMS license file (gamslice.txt) are reported both in the log file and in the lst file. Below are some typical error and warning messages and instructions how to overcome them.

No License File present

Without a license file GAMS will not work. If you have received a license file (gamslice.txt), follow the instruction from the previous section. Do not try to rename it or to modify the contents of the license file. Without a license GAMS will give you an error message like the one below:

*** No license specified and no gamslice.txt found in standard locations.

License File Invalid or Corrupted

Running GAMS with an invalid license will give you an error message like the one below:

*** License File validation failed

Do not try to modify your license file, any change will break it. If the original license file is no longer available, please contact and ask for a copy of your license file. Please attach the license file you are currently using. This error also pops up, if you are using a license file, which was issued for a different platform.

License File expired

If are trying to run an old license file with a newer GAMS distribution, you may get an error message stating:

*** License file too old for this version of GAMS.
*** Maintenance expired 2840 days ago.
*** More than 60 days since expiration, sorry...
*** Run an older GAMS system or renew the license

Replace that GAMS system with the one you got together with your license file (use the CHK4UPD utility mentioned above to find out the latest version you can use with the current license; old systems are available on request from or update your license to the current version.

No License (for a particular Solver) found

If one of the solvers you are trying to use (or is selected as the default solver) is not included in your license file and the size of the model exceed the limits of the free demo or community version, you will get an error stating:

*** No license found
*** To update your license, please contact your distributor.

Check whether the default solvers for a particular problem class are included in the license. Please note that some of the solvers call other solvers as a sub-solver, e.g.:

  • GAMS/DICOPT requires an NLP and a MIP solver
  • GAMS/SBB requires an NLP solver
  • MPSGE: If GAMS/PATH is not included in your license, please select GAMS/MILES, which is included in the base system as the default solver for MCP problems.


License file too old for this version of GAMS

The complete message is:

*** License file too old for this version of GAMS.
*** Maintenance expired xx days ago.

If GAMS continues working, you can ignore this warning. However, any forthcoming GAMS distribution will most likely not work, but downgrade to the limits of the free demo system.

License File has expired xx days ago

This warning (without further error messages) indicates that the time limited license (e.g. an evaluation license) will stop working soon.

The GAMS/BASE Module

The GAMS/BASE module includes:

Additional Limits for the Demo and Community License

The model size limits enforced by GAMS are:

  • 2000 variables and 2000 constraints for linear (LP, RMIP, and MIP) models with a demo license
  • 1000 variables and 1000 constraints for all other model types with a demo license
  • 5000 variables and 5000 constraints for linear (LP, RMIP, and MIP) models with a community license
  • 2500 variables and 2500 constraints for all other model types with a community license

In addition to the GAMS model size limits, the solvers might impose stricter limits when running with a demo or community license. We use m for the number constraints, n for the number variables, nd for the number of discrete variables, nz for the number nonzeros, and nlnz for the number nonlinear nonzeros:

  • Antigone, Baron, LindoGlobal, and Octeract require m≤50, n≤50, and nlnz≤50 with a demo license.
  • Antigone, Baron, LindoGlobal, and Octeract require m≤300, n≤300, and nlnz≤100 with a community license.
  • Cplex and ODHCPLEX require m≤2000 and n≤2000 with a pro-bono community license.
  • Decis and Knitro require m≤300, n≤300, nd≤50, nz≤2000, and nlnz≤1000 with a demo and community license.
  • Xpress requires m+n≤5000 with a community license.
  • In addition Gurobi requires a license file from the vendor to operate.