Plus, you get to stay in touch and advertise via a monthly email: “You didn’t do any searches so we’re giving you next month for free, here are all the cool things you could do:…”.
You can do that, but if they don’t interact with your email either, you may be better off not doing so. You get worse delivery rates if you constantly send email that gets ignored.
They send by default an email every month when the payment time is approaching, so I assume they may just send the same email and state that the payment amount is covered by the previous month. They have really good practices at that.
Yet Kagi is one of the very very few services I've seen that sends a monthly reminder that they are ABOUT to charge you... And you have time to stop it. Typically I only ever see something like that with shipped goods where they might have to deal with a return + cancellation
That's really nice sounding and comforting. I've been a little on the fence, but Google has become such absolute garbage lately that I've had to frequently use Bing in order to find something that should be one of the first results. This may just be a better model.
People also forget that they're subscribed to something (or that they signed up for emails either explicitly or implicitly), so they just report to Google (or whoever) as spam. I'm sure that's why I get a lot of email (mostly in my Gmail Promotions or Updates tabs that are from companies that scanned me at some event or whatever or I ordered something from.