Your account balance represents bot execution time instead of dollars. The least amount of time you can purchase is 1 hour for $1.00. The more time you purchase, the cheaper it gets. When you sign up, you get 10 minutes of free execution time to try out the service.
What happens to my bots if my balance reaches zero or becomes negative?
Don't worry, your bots will continue to run. You will receive an email notification to top up your balance. If you don't top up your balance, after a certain grace period, your scheduled bots will be paused and you won't be able to manually execute them either.