To play many purchases from the iTunes Store, you must authorize your computer using your iTunes Store account and password. (Authorization helps protect the copyrights of the purchased items.)
You can authorize up to five computers (Macintosh, Windows, or both) at a time. To play a purchased item on a sixth computer, you need to deauthorize another one. An iPod doesn’t count as a computer.
You can authorize or deauthorize a computer at any time. Be sure to deauthorize a computer before you sell it or give it away.
Here are ways to authorize or deauthorize a computer:
To authorize a computer to play iTunes Store purchases, choose StoreÂ > Authorize Computer.
To deauthorize a computer, choose StoreÂ > Deauthorize Computer.
To deauthorize a computer to play spoken programs purchased from the Audible website, choose AdvancedÂ > Deauthorize Audible Account.
If you forgot to deauthorize a computer you no longer own, you can deauthorize all your authorized computers at once. You can use this method once a year.
Choose StoreÂ > View My Account, and then click Deauthorize All. If you don’t see this option, it’s because you don’t have five authorized computers.
If you have trouble deauthorizing a computer, visit the website below.