When you enroll in a course in the free audit track, you will have access for the number of weeks listed on the enrollment page. You’ll see a banner within the course showing the date your access expires:
After the expiration date you would need to pay and upgrade to the verified certificate track to regain access in this session, or enroll in a future session when the course is offered again.
Upgrading to the verified track will give you access to all materials, including graded assignments, until the course end date. Upgrading will not change or extend the course end date. You’ll still need to pass the course before it ends in order to earn a certificate.
After the course end date, as a verified learner, you will have access to archived course content and materials, as long it exists on edX.