FetchApp puts you in control of when customers can access your files. Specify when download links expire by time (1 day, 3 weeks, forever, etc.), quantity (3, 5, unlimited downloads, etc.), or both (3 days or 5 downloads, whichever comes first).
Once orders have been received in FetchApp, you have the ability to expire or reopen them on an order-by-order basis for ultimate control.