In order to transfer Apps from your iPad to iTunes on your computer just follow these steps:

  • Open iTunes on Your Computer.
  • Choose Store Menu>Authorize Computer.
  • Use the Apple Account information you used for your iPad to authorize it at iTunes.
  • Connect iPad to your computer.
  • Click on “Transfer Purchases”.
  • Make sure you avoid clicking on Erase and Sync or you will delete all your other content.

Only purchases made through iTunes will transfer from your iPad to iTunes. For all other content, make sure you are set up to sync with iClouds and your apps will backup to iClouds during the next sync.

Resource: Apple Support