Not by using our own download-fulfillment system, really, since the download links we issue to buyers expire after a maximum of 9 attempts (or less, according to your settings), but you might have the buyer's payment data sent to a script on your site that would enroll them in a membership system you also maintain on your site.
It's not clear what role E-junkie could provide that you couldn't do just using PayPal IPN along with a membership system to manage access to your download pages like, say, FrontDesk (just one system we've heard of offhand):
http://frontdeskapp.com/
