When does Heroku stop processing requests?

Question

Bots

Created a PHP bot for VK. For some reason I stopped answering questions. I go to the server, and there is an inscription: "Page is not available
The site <name>.herokuapp.com cannot process this request yet.".
How would you suggest to solve this problem. To be honest, the bot works with parsing other sites. Does it somehow affect this problem?
Or is it better to take a paid hosting?