Reporting will help you know whether users are making their way through your course overall, and who specifically has completed (or needs to complete) the course. You can even see at which step in the course users left off.
View overall course progress
This gives you a quick overall view of the progress of users that have been assigned or have self-enrolled in the course (if not restricted).
View overall step progress
Click a specific course title to view how many users have completed the course and individual course step progress.
View individual user progress
See which users have yet to start the course and which completed it (or what part of the course users dropped off, if incomplete).