Read the conditions of the purchase. The cdkey sites generally tell you if the key is region free or not. If it doesn't say, look elsewhere as you generally won't get a refund for this sort of stuff.
If you want to pay more unnecessarily that's up to you. I just pay to get the key and activate it on Uplay, and get in on co-op action. $19 for a new release game, can't beat that.