With every course you have the option to set up the course completion settings a few ways. You can choose from:
Selecting this option will allow students to have access to the course as long as the course is set to this, even if they completed all elements in the course. This also means that they will also be able to revisit the elements unlimited times unless you have set the revisit options to limit them.
If you choose this option it is not necessary to select any of the 4 choices below it if you don’t want to put a time restriction on the course for the students. Selecting any of the additional options will let you put the time restriction on the course if needed.