From 99¢ to a 99¢ in-app purchase

My hobby app Rounds was 99¢ for its first 2 years. In September, I made a bunch of changes. I made the app free and instead offered a 99¢ in-app purchase to unlock a full palette of colors.

Blue is sales.
Red is current installs.

Note that current installs were depressingly small & flat for a very long time. As a small number new users purchased and installed the app, an equally small number of old users uninstalled and moved on.

Going free yielded a nice spike in installs, but no equivalent bump in sales. Ratings are also down from 4.8 stars to 4.5, mostly due to a handful of drive-by one-star reviews.

Clearly I need to figure out how to improve conversion.