Thank you for testing Keychat. 

We are adding nsec login functionality and plan to release a new version this week or next. 

According to statistics, the average user sends about 50 messages per day, costing around 50 sats. With one cent currently buying approximately 16 sats, the daily cost is about 3 cents, and the monthly cost is about 90 cents. We believe that a pay-per-use model is more reasonable than a subscription model.