Changing a Download Link

I have a store that I am selling memberships to. I need my customers to have unlimited access to the digital products once they purchase a membership. Is it possible to change it so the links works forever. I am seeing that it expires in 24 hours and I do not like this.

I think you can create a password protected page, attached digital file here. Then in product, you can send your customer a txt/Word file, with link to this protected page, so when the link expired, they still can access protected page to download digital file