Limits to Sharing
While you can share most of your music, and playing music from a shared library is transparent, there are several limits you need to be aware of. You saw above that only five users can access your iTunes library in a given day.
In addition to this limitation, other users cannot listen to protected music files, including any purchases from the iTunes Music Store - unless their computers are authorized to do so. If you’re sharing music at home, you’ll want to authorize each computer (this means you enter your iTunes Music Store user name and password when asked) so everyone can listen to your purchased music.
You cannot share audiobooks purchased from Audible.com, but you can share audiobooks purchased from the iTunes Music Store. If you listen to an audiobook via music sharing, the file won’t save a bookmark when you stop listening; you’ll need to make a note of the exact time you left off so you can pick up again at the same point in the story.
Finally, you cannot use a shared library as a source for the Party Shuffle playlist, nor can you access music on an iPod connected to another computer on your network. And, because of copyright concerns, you cannot copy music to or from a shared library.