Even the most efficient people go through a phase of struggling with deadlines. Having a limit of time not only motivates a person to work faster, but also to achieve better results.
If you want to make a limit time for your Learners in your course, you can set up a deadline. For this, open its "Settings"
Then, open "Deadlines Settings" and chose the type of deadline, that suits you the most:
"Due date" deadline type will open access to the Learners for completing the course to a defined date
"Days" deadline type will give an opportunity for the Learners to complete the course for a period of time