I don't think a trust should be necessary. A plan for longterm sustainability should be.

The streaming video service Nebula, for example, has a lifetime membership. The company was very straightforward with potential customers: this is not their best deal, it's explicitly meant for people who want to help support the company (or who prefer not to have ongoing subscription costs), and they are doing it as an alternative to seeking outside investment money. The money they raise won't go into a trust, but into expanding the business in the same way a company might if it went to seek venture capital.

At the time I signed up for it, it cost roughly 10 years' worth of subscriptions.