To get your own license for the Studio version (which has many important unlocked features compared to the free version), simply follow these instructions:
1) Download, install and update GameMaker Studio from YoYo Games. Ensure you are using the 'beta' channel.
2) On the 'Welcome' tab, click the right arrow.
3) Click 'Upgrade to Standard for free now'.
4) Enter email and follow instructions to receive your license, and then enter to register it.
Good luck with your game creation designs! I hope one of you makes the next big indie hit.