Seban69: And what if I dont have it registered with my account since I recieved this as a gift from my friend on a pendrive?
No. It doesn't work like that. I will assume this is actual ignorance on your part though:
9. Can I install one game both on my laptop and desktop computer at home?
9. Can I install one game both on my laptop and desktop computer at home?
Yes. We do not limit the number of installations or reinstallations, as long as you install your purchased games on computers in your household. So yeah, if you've got a render-farm in the basement, you might actually break the world record for the number of legal Fallout installations in one household. However, if you think about installing your game on a friend's machine or sharing it with others then please don't do it, okay?
Your friend did not gift this to you. He actually bought it for himself. Which means you need to kindly uninstall the game or better yet buy it from GOG yourself.