The maximum day-rate applies per calendar day.
The maximum day-rate will start after 8 hours. So you will pay for max. 8 hours per calendar day. As long as you start a vehicle on the same day and also finish the ride, this rate applies. The next calendar day starts from 00:00.
Good to know:
The maximum day-rate only applies to you if you have a Hely FLOW package.
The maximum day-rate only applies if it concerns one continuous reservation.