Or, for example: You activate it, you go in game, you get an activation code or whatever. Say you did that, typed in your ID. When you go and check, if your ID is the same as entered, you'd get a message that would activate it? But someone else could screw with it even though it wasn't their own. Which is why it would have an activation code that you'd insert in-game to activate it.
I forgot my train of thought.