If you choose to take a course for free, you’ll have access for the duration of the course, even if you join after the course opens. You can see when free access to your courses expires in Your Learning.
[Image descriptor: The above image shows a course listing from within the Your learning section with the number of days left of free access shown in the top right corner of the course cover image. 35 days is the number of days left in this example, and it has been highlighted with a green square around the numbers.]
For example, when you join a 4-week course, you will be able to access it for 4 weeks (the duration of the course), even if you join after it first opened for enrolment. Once this period has finished, you'll see a message saying 'Access Expired'.
If you'd like to study the material after your free access expires, you can purchase an upgrade to give yourself unlimited access. You can find more information about the difference between free and upgraded courses in this article: Free courses, upgrades and courses you pay for