iTunes, iTunes Store
Authorizing and deauthorizing a computer allows you to manage which computers can sync or use apps, audiobooks, books, music, movies, or other content you've purchased from the iTunes Store.
You can use or sync your purchases from the iTunes Store on up to five different computers (these can be any mix of Macintosh or Windows-compatible computers). When you sync or play an item you've purchased, your computer is "authorized" for purchase using your Apple ID.
- In order to enable Home Sharing, Automatic Downloads, or downloading of past purchases, your computer must be authorized for use with your Apple ID.
- Songs you encode in AAC format from a source other than the iTunes Store, such as your own audio CDs, and iTunes Plus content (music and music videos) do not need to be authorized.