You must always be on the current/newest public version of GMS2 in order to use your licence, so you may be required to periodically update your install in order to continue using GMS2.
It does not permit you to test using the higher-performance YoYo Compiler (“YYC”).
It does not permit you to create shareable executable copies of your game.
The new free release is essentially the full version, with a few caveats: We did a Closer Look at GameMaker several years ago, it is a long running 2D game engine that has been used to make dozens if not hundreds of successful commercial games and countless indie titles. As we predicted several months ago when YoYoGames was acquired by Opera, a free version of GameMaker Studio has been released.