Pay for what you use. It couldn't be more simple.
One credit is deducted from your account each time a new job is created. To add more, you can either purchase as you go or set up automatic top-ups. There's no minimum spend and no pressure on you to buy more.
Your credit card will only be billed when you make the decision to purchase more job credits - there are no other payments for you to worry about.
If you use SMS messages on the app for reminders, each text will only be 10c - that's just 0.1 credit each time.