That's what I thought, I've actually been thinking to allow the e-book to be downloaded only once a day and since it's a digital file, the person who downloaded the file has 24 hours to delete it from their system.

Obviously there's no way to know that the file has been deleted, just as there's no way to know if a real book has been photocopied.

But I'm just sharing an e-book once per day, just as if I were lending a real book to thousands of people once at a time.