HT4539: iTunes Store: How to enable Automatic DownloadsLearn about iTunes Store: How to enable Automatic Downloads
Currently Being ModeratedJun 5, 2013 12:21 PM (in response to kuropuss2004)
If you purchased it on your iPad then it should have downloaded on your iPad - when you have audiobooks on an iPad you will get an Audiobooks option under the More button at the bottom of the Music app.
Automatic downloads won't work with audiobooks, they are currently a one-time download from the store so will only be downloaded on the device that you buy them on (so they also won't appear in the Purchased tab for re-downloading). You should be able to copy it from your iPad to your computer's iTunes via File > Devices > Transfer Purchases so that you can take a backup copy of it - it should copy over to the Books part of your iTunes library.