Respectfully disagree. An obligation to maintain a service in perpetuity for no revenue becomes a huge unfunded liability.
What if the app falls out of favor and new marginal revenue can’t cover fixed costs?
What if the business wants to innovate in a way that dramatically changes its cost structure (maybe introduce a feature that requires a usage based license)? Sure you can gate older users but how long do you have to maintain a separate set of features for them?
Obviously it’s the apps responsibility to make a fair deal with users and stick to terms offered. Sure some companies can make a model that amortizes an upfront payment effectively over decades. In reality though, all that really matters to a company is new cash that pays expenses. If you’re not contributing to that at some point you are no longer the customer.