Q: I have several songs that I have purchased from the iTunes Store using the iTunes App on my iPhone. I can’t get them to transfer to iTunes on my computer. What am I doing wrong?
A: Normally any tracks purchased on your iPhone or iPod touch should automatically transfer back to your computer as soon as you sync your iPhone, provided that your computer is authorized for the same iTunes Store account that was used to purchase the tracks on the iPhone itself.
You can manually authorize your computer by choosing Store, Authorize Computer from the iTunes menu and entering your iTunes Store user ID and password.
Note also that if you’re managing the content on your iPhone manually rather than using automatic sync, your purchased tracks may not automatically be transferred back. In this case, you can force this transfer to occur by selecting the Transfer Purchases option from the iTunes File menu while your iPhone is connected.