My nephew has been asking me to play World of Warcraft with him. I have never played it before and have only watched him for a few minutes. I am thinking of joining to be able to play with him. If I do play it, I understand there is something like a $15 a month fee, which is a little high, but I can do.

So, the question is, do I need to buy the game as well? Can I copy the game from his machine? If I copy the game, and pay the monthly fee, is that all Blizzard cares about, or is there some kind of key code the game checks for?