Uruky [1] (a Kagi alternative, but simpler and EU-based) does this in a more intentional way: You can only pay once for a period of time (one, three, six, or twelve months), there is no subscription! If, after that period, you want to keep using it, you have to pay again.

This was mainly done for privacy reasons, so less data needs to be stored in the account (it also only uses a randomly-generated account number, like Mullvad), but honestly, we don't want people paying that don't use the service.

And you're right, it makes "making money" much harder, but also, feels more honest.

[1]: https://uruky.com