iTunes - Automatically download content purchases made from the Store
You can configure iTunes to automatically download the purchases (apps, books, music) made from the App Store, iTunes Store....
The procedure is as follows:
- Open iTunes and sign-in using the Apple ID (used for the purchases).
- Click on the Store menu > Authorize This Computer (Apple ID required).
- Click on the Edit menu > Preferences > Store.
- In the Automatic Download section, check the following items:
- Click on Ok to validate.
The procedure for iOS is explained here: http://ccm.net/faq/34438-ios-automatically-download-purchases-made-on-other-devices