I paid for the ad-free version but still get the splash screen telling me to buy it every time I open the app.
Also, if there were a way to make it untimed I would pay for that. It’s satisfying to untangle the knots, but racing to beat the clock is not the fun part for me.

I would pay to remove the ads, which are frequent and obnoxious, but since there’s no option to do that, I’m uninstalling.

This is a very useful tool for flamenco guitar students. I find the clock representation to be helpful when trying to learn tricky rhythms. By visualizing where what I am playing falls around the accents I can transition quickly to feeling where things should go by listening. It's a relatively expensive app, but for me it's been totally worth it.