To get access to technology and support by the GTP for free, companies developing software within the EU have to sign the GTP SIG Membership Agreement - in our opinion a small price to pay for what you get in return :-).
The agreement was voluntarily kept as concise and liberal as possible. It consists of a general and a specific part.
The General Part contains standard game middleware software licensing stuff, such as Confidentiality, Copyright & Ownership, etc.
The Special Part contains the following points:
SIG Membership Offical: You agree to allow us to make it known to the world that you are a GTP SIG member. Basically that means free exposure for your company ;-)
Use of GTP technology/software: This is the good part - it allows you to use GTP technology for any purpose (also commercial, of course), condition to the following four logical restrictions...
EU Focus: Since the GTP is funded by the European Union and is here to boost software development within the EU, this is what you agree to do - develop software using the GTP libraries within the EU :-)
Credit: Same as with many libraries, you must state that your are using GameTools techology in your product, when shipping it.
Scientific Results: GameTools represents leading edge research, so naturally the participating universities must have protection against their results/sourcecode being used by someone else to produce scientific publications. Remember, you get full access to optimized sourcecode if you are a SIG member, something which is not the norm in the academic community !
Library Creation: This is also a natural one - since the GTP is supplying its libraries for free to SIG members, we do not want a SIG member to create and/or sell libraries based on the technology.