When you purchase this game in a store, you’ll be getting a World of Warcraft CD key. This is issued to confirm that you actually purchased a copy of the game. It is always a good idea to store your WoW CD key in a safe place, just in case you ever need to reinstall the game or if you have problems with your account. However, if you have misplaced your World of Warcraft CD key, you may run into some problems.
Luckily, there are other ways to restore or get a new WoW CD key. Whenever an authentication key is issued, it is permanently tied to a specific World of Warcraft account. That means that it cannot be used again, and that the account name can never be changed. For example, if you want to use a friend’s copy of the game, you would be forced to play under their user account.
However, you can turn this to your advantage by using an older World of Warcraft CD key. Some players that want to get ahead quickly and bypass a lot of the early questing, will use a pre-existing WoW CD key to take advantage of an established account. There are some downsides to this, especially if that user developed a bad reputation, but for some players that don’t have a lot of time on their hands, this is the single best way to take advantage of an already established character that has skills, money and has already progressed through several levels of the game.