You can easily access a record of your saved Designer PDfs from the Proofs menu in the Designer administrative page. You may click on the download icon on the right-hand-side of the menu to download a saved proof file. The Product ID and Date/Time is listed for each save:
You can also choose to delete any saved proofs using the red X on the right hand side of the Proofs menu. You can search for specific proofs using the search bar at the top of the menu