If you purchased items from the iTunes Store and the only place you have them stored is on your iPod or iPhone, you can transfer them to any computer that is authorized for your iTunes Store account using iTunes 7 or later. This feature adds an extra layer of protection against losing your valued purchases.
If you want to transfer iTunes Store purchases from an iPod or iPhone to a computer, be sure to authorize the computer before connecting the device. To authorize, follow these steps:
1. Open iTunes.
2. From the Store menu, choose Authorize Computer.
3. In the dialog that appears, the Apple ID button is selected by default. If you have an AOL account, select AOL.
4. Enter your Apple ID or AOL screen name and password, then click the Authorize button.
If the iTunes Store purchases on your iPod or iPhone were purchased with multiple accounts, you will need to authorize the computer for each one.
To transfer iTunes Store purchases from your iPod or iPhone to a computer, follow these steps:
1. Connect your iPod or iPhone to the computer. If your iPod is synced with another iTunes library, the following dialog may appear:
2. Click the Transfer Purchases button.
iTunes will begin copying any purchases made with any account that the computer is authorized for.
If when you connect your iPod or iPhone you are not prompted by the dialog above, it could be that the option "Do not ask me again" was previously selected. Fortunately, there are two more ways you can copy your purchases from your iPod or iPhone.
After connecting your iPod or iPhone to the computer and its icon appears in iTunes, you can choose Transfer Purchases from iPod from the File menu.
Or you can right-click (Windows or Mac) or Control-click (Mac only) your iPod in the iTunes Source list, then choose Transfer Purchases from the shortcut menu that appears.
Please note that this feature only works for items that were purchased on the iTunes Store. Any items imported from audio CDs or acquired from other sources will not copy from your iPod or iPhone to the iTunes library.
Related documents
302392: "How to back up your media in iTunes"
93366: "iTunes for Windows: How to copy purchases between authorized computers"
93063: "iTunes for Mac: How to copy purchases between authorized computers"
http://docs.info.apple.com/article.html?artnum=305465
