Scramble Redirect

So I’am selling an ebook that I wrote on my wordpress website. I’ve uploaded the ebook onto my wordpress using ftp so there is a link. so when the customer purchases the book they get the link to it after paypal verifies everything. Problem is once they get the link, they can just share it. Is there a way to hide the address bar or scramble it somehow so this can be avoided? Thank you for all the help!