How do I stop people sharing my digital product?
Updated
Accept the honest answer first
You cannot stop people sharing a digital product completely. Any file a buyer can open, a buyer can copy. What works is making casual sharing awkward: give each buyer a personal download link, print their email quietly in a footer, and limit downloads per purchase. Heavy protection punishes paying customers.
The realistic goal is friction, not a lock.
What actually helps
Personal download links rather than one public link. A small footer with the buyer’s email on each page. A sensible limit on downloads per purchase.
These deter the "sure, here you go" kind of sharing, which is nearly all of it.
What costs more than it saves
Passwords, DRM, disabled printing and copy protection. They frustrate paying customers, create support tickets, and are easily defeated.
You will lose more money to annoyed buyers than to pirates.
Compete instead
Updates, support, a community and new versions are things a leaked copy cannot provide.
Sellers who build those stop worrying about leaks, because the leaked copy is the worse product.