The problem is that no one knows how long it has until this case, when the service will do its task. And I want to maintain the server and avoid advertisers with corporations. I want to ask for a modest, tiny price for time: like one dollar for a month or five dollars for a year. That should be enough to pay for a notional fifty years up front to cover an "insurance claim" for sure. And it could work as a form of donation: like paying a two hundred years in advance just for me and my work.
I'd make a one-time payment, if it weren't for the narrow focus and "useful but not for everyone", which makes it unlikely I could hope for the number of users. But I also don't know how best to balance the subscription so that it's fair and seen as an investment in case the worst happens, rather than something useless which suck money from the pocket.
What are your thoughts on this?