Just a notice: If you have NAY version of Game Maker Studio already installed, you have to uninstall them, then delete Windows Registry entries for GM Studio and 5tudio. This completely removes your Free and MIPS licenses from your system.
If you don't, everytime you try to reinstall GMS it will automatically use your old license. There was no guide for this. I had to dig around my registry manually as I suspected that was the issue.
Waiting to see if the author will approve my posts on his comments about this.