How to transfer purchases from iPhone into iTunes library
Solution 1:
You can do this in the iTunes menu at the top of the screen: File :: Devices :: Transfer purchases
As simple as that.
Solution 2:
You'd better transfer your purchases first.
- Connect your device to the computer. Wait for its icon to appear in iTunes.
- Go to File > Devices. If you're using iTunes for Windows and can't see the menu bar, learn how to turn on iTunes menus in Windows (http://support.apple.com/en-us/HT202662).
- Choose Transfer Purchases from [device name].