Paywall - updated
To reply to developer comment. Simple answer. Run ads. Keep it free. Run banner ads. Run one pop ad at startup. Probably make you more money than a one off fee.
Response from developer
Yep, got to be paid for the 1000+ hours I’ve put in to this app. People think it makes me rich, it literally makes $150 a month. Follow-up reply - I tried ads 2/3 years ago. They are a horrible user experience, unreliable, and made about $2 per day. The app is not as popular as you may think. Unfortunately, the premium upgrade for 2D replays and damage log is the only way to make it worth my time. 90% of the app is free.