I'm not sure why you would need or how you would use a license for an in-game programing language.
More than one person has already created complete simulators where you can test out code. FB were kind enough to tell people pretty much every detail so far of how the language works. (such as execution order for dense math statements, how device field updates work)
Check out
CYLON to find tools and info, or if you really want to dig into the details. Also the wiki has a complete reference for Yolol, as well as pages for all the ship devices that include device fields with descriptions of their function.