It's a growth hack. Once they take off, startups usually drop the lifetime tier. I don't think you have any guarantees in general. I emailed one YC startup o

It's a growth hack. Once they take off, startups usually drop the lifetime tier. I don't think you have any guarantees in general. I emailed one YC startup offering a lifetime tier asking what would happen to the lifetime subscription (before buying it) if they went out of business. Their response was that it would be refunded. In the average case, something like this seems reasonable to me: refund = cost_of_unlimited - years_of_usage * cost_per_year