Yes, and he wants to get the keys from GameStop US, which falls under the US region and would, logically, be US-region keys.
This is complicated, huh?
Let's go through this one last time: Yes, there are region locked games; although this is primarily when purchasing from cheaper regions such as Russia because there was a significant problem with people doing this. This doesn't really affect games purchased between the EU and US regions.
Though nothing is ever completely certain, this hasn't ever been a problem before, I really doubt it'll be a problem now. Speaking from experience.
Think that about sums it up?
NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOO!
haha touché