hi

I created a website for sale purchase of a book! The problem I am facing here, is that as soon as the user purchases a book, he's provided a link, from which he can download the file!

But, if some user, distributes the URL, the company will bear a loss. So, what I want is to provide the link to the book in such a way, that the user who has purchased the book can only use it and also on that very session, and later on if the URL is accessed directly, the book cant be downloaded!!

Any ideas, how to go about it?