Ability to sell a shop-wide subscription that allows subscribers to download all, or specific content for free during their active subscription period.
Also, with ability to have either unlimited downloads, or a specific limit.
Here are some examples, with different models:
  • Creative Market, monthly or yearly subscription and download based on credits, or purchase assets normally
  • Envato, monthly or yearly subscription and download unlimited, or purchase assets normally
  • Framer auth, monetize members-only access https://framerauth.com/
  • UI8, pay once lifetime subscription and download unlimited, or purchase assets normally
There are many other examples of libraries I can provide that work on this model, but I think this is a good start! :)