Asking that after saying "unless my friend makes a copy..." looks like you are trying to find out how much work will be required to pirate the game. At the very least, it is in poor taste to talk about pirating software on the company's official forum.
CD keys don't do much to prevent piracy, unless it is for software purchased online (and the key can be tied to a name/address/phone number), there is a mandatory registration (Windows XP), or it is for an online-only game where a server can keep track of keys and make sure two people can not use the same key at the same time.
