Here you can see how to generate a time locked key. Time locked keys are used in many situations, where you need to limit the user's ability to work on your workstation to a certain time.
For example:

• If you want to sell time on your workstation in Internet Cafe.
• If you want to allow people limited time on a terminal workstation
• Factory workers, to get a limited time to log their work
• Students in the classroom, to get limited time in front of the workstation