PDF Ebook software w/security feature

I'm sorry for putting this in the White Hat SEO thread (thank you Mod for moving this to a more appropriate spot), I just wasn't sure where to place this request.

Could someone please tell me the name of the PDF/Ebook software which has a security feature which allows you to disable access to it? There was a thread here before (I have searched to no avail) in which one of the senior members -- it may even have been a mod -- spoke of an incident in which someone bought his ebook and then later tried to get a refund, then the purchaser was pissed because they could no longer access the ebook. If I remember correctly, the software was relatively inexpensive, but for the life of me, I can't recall the name of it...

Does this sound familiar to anyone?

Thanks!

go visit http://verypdf.com they have a brilliant password remover for pdfs if you want to write ebooks with a password protection that you can remove from your desktop then your loking at ebookgenerator 3 just put it in the search engines and it will come up