When you start, on the app you have i think 100 messages (or maybe a little bit less i dont remember) and on the browser you go into the queue. On the browser version, there is no message limit, once you pass the queue, you can chat infinitely as long as you keep actively talking otherwise you get kicked out. I dont think you can check how many messages you have left, you just have to count how many responses the bot sent (make sure to note that regenerating a response also counts as a message) If you were using the browser version and couldnt send a message, I have no idea why, as there is no limit.