I understand hating subscriptions but in this case a one time payment would require Kagi to continually gain an increasing number of members for eternity or run out of operating money and shut down. You could hope for something donation-based like most Lemmy instances, but just expecting other users to cover your costs is selfish. There's a difference between asking your users to at least pay what they're costing you and rent-seeking with things that don't or shouldn't cost you a dime to provide. Subscription services have existed for a very, very long time (see: any government that collects taxes), it's only recently and due to greedy trends that they've been becoming a nuisance.

If you want to empower your own sense of privacy and security, you'll need to accept that you've been paying for services with your data or supposed ad views for decades, and some of those services cost money to run.

I agree that subscriptions for apps becoming the norm is pretty terrible. You should just be able to pay once and use the version you paid for forever, and optionally upgrade to a newer version for a price.

But Kagi is a service. You using their search actively costs them money, so they wouldn't only not gain any money from you after your one-time purchase, but actually lose money.