TTCN-3, as a language, doesn't have any license, it is free of charge for everyone. You just need to download it from the download/TTCN-3 standards menu.
If you want to start your own business, you have a few alternatives:
- using a commertial tool; they are listed in the Tools menu. In this case you need to ask the license fees and conditions from the tool vendors;
- use an open source tool; there are some listed in the tools menu and there is one more that is not yet listed, because its source code will be published in a few weeks:
projects.eclipse.org/projects/tools.titan
- writing your own tool, but I doubt it is worth to do economically.
Best Regards, Gyorgy