iTunes automatically syncs everything you’ve downloaded or purchased on iPhone to your iTunes library when you connect iPhone to your computer. This lets you access the downloads on your computer and provides a backup if you delete purchased content from iPhone.
Purchased content is synced to the “Purchased on <name of your iPhone>” playlist. iTunes creates the playlist if it doesn’t exist. iTunes also copies your purchases to the Purchased playlist that iTunes uses for purchases you make on your computer, if that playlist exists and is set to sync with iPhone.
Downloaded podcasts are synced to the Podcast list in your iTunes library.