I bought license from steam. And there writes that you have 3 install rights. My question is, if I make clean installation to my pc, format everything and reinstall again. Will my 3 rights be 2?
I'm pretty sure the answer here is no... the YoYo Account page is what controls this and not Steam, and it also shows the installs you have currently activated. Basically, you can have GMS installed on up to three machines, but if you want to install it on a fourth machine, then you need to de-authorise one from your YoYo Account.