Precisely. I am not going to keep former clients in my portal indefinitely--they'll be deleted after a year or so. If they have not downloaded their copies by that time, they will have to pay me because I also send e-mails with links to the documents, and SPECIFICALLY say they need to immediately save a copy for their records.
As to when I retire or, more likely, sell, I still have all the same files on my computer and in backups, but I am starting to go through and delete anything older than 6-7 years. That is the longest I will keep anything outside of portals.