[nathan_long]

You can require a password to download the book in the first place, which is like a "please don't steal" sign. Many people won't. Those who will can't be stopped by any technological means; DRM doesn't work, and devalues the product for honest customers.

You can hope that the freeloaders end up increasing the book's popularity and attracting more paying customers. But there isn't much you can do to influence that except make good stuff.

[madrobby]

I don't have a general download link, when you buy it I'll send out an email with a personal download link that will expire in a week or so, and can only be used 5 times.

Of course you can just write to my support email box and I'll send you a new link if you loose the file. I also send out free updates whenever I update the book.