I think you've chosen the wrong vehicle for anxiety. A niche product like Kagi cannot have such a huge impact on your life that it motivates this kind of fear. Enjoy it while it is good, and if it doesn't satisfy your demands in the future you can cancel the subscription.
That's just life, there are no guarantees. Part of grown life is that we cannot anymore transfer our insecurities onto other people like when we are children. There's nobody who can promise to take responsibility and make sure that you personally stay happy.
Maturity is also to understand that it is insulting and comes off as hostile to accuse people of bad actions that they might or might not do in the future. How would you feel if such accusations were directed towards you?
If I buy a motorcycle, I'm going to ride it happy, and not worry if next year's model isn't any good.