With Ebook Weaver you can protect your e-books by password and also set an expiry date, useful for shareware applications.

However, if want more control over your e-books like the ability to terminate them when you give a refund take a look at Remote Locker.

Ebook Weaver is fully compatible with Remote Locker which means you can track when your e-books are being used, by which IP addresses and you can even terminate them in the event of a refund.

Never again will your e-books be illegally copied, sold or distributed.