Air conditioning units are always high energy consumers. There is nothing more annoying than guests who leave the air conditioning on for long periods of time even when they are not in their apartment, cottage, or room.
With a coin-operated meter, you can limit these costs.
With the LT3500, for example, you can deposit an amount for your guest into the meter so that they can use the air conditioning for a certain period free of charge as a service. Once this credit is used up, they can add more coins themselves.
The LT3500 only starts counting down when the air conditioning is turned on. The air conditioning is never completely disconnected from the power supply, so it is always possible to start the air conditioning with the remote control or similar. The timer only starts running when power is requested for cooling. (You set all of this on the coin meter, and you do not need to make any adjustments to the air conditioning unit itself).