Allow Students to Retake is an offering option that when enabled will allow the student to register for the course again, and pay again if applicable, and view it through to completion. Once a student completes a course, which means they have completed the last course element, they can no longer view any of the course materials; they can only view their grades under the My Gradebook tab. The only caveat to this would be if the course is being delivered in such a manner that your are controlling the duration of course/element delivery through the use of advanced delivery options or element revisit settings. In this case the student would have unlimited viewing of the course content until such a time as the course is marked complete based on the delivery options you have selected.

If the Allow Students to Retake option is not enabled the student will only be allowed to register for the course one time. After successful registration by the student the course will no longer be displayed in the Catalog.