One time payment since it runs whisper locally. Autoupdates through the app store, and I have a lot of folks emailing me positive, negative and improvement feedback.
It is a lot of randomness. Some weeks are low and when it got a small mention in a popular article I saw a sudden inflow of traffic, downloads and purchases.
So far Ive been ok paying the apple tax. Its a little hard going through the hoops to get it through the app store( I kinda understand why they do a lot of it ) but it provides a lot of free discovery and I spend 0 time on payments, refunds, disputes, handling a CDN to distribute binaries etc. Negative reviews without basis are the only thing that bother me, for some reason I seem to take it personally.