Does my guest receive a notification before their credit runs out?

Yes, the guest automatically receives a message on their phone as soon as their credit falls below a certain limit, well before it actually runs out. That message appears on the same screen where they can already see their consumption and credit, and they can top up directly without an app or account. If no one responds to the warnings and the credit does reach zero, the power shuts off. As the landlord, you don't need to arrange anything for this; the limit is already set correctly.