All courses you purchase, you have an unlimited amount of time to complete. You can take the course as many times as you like and you can take the test as many times as you like. We always record your best score so if you pass then fail later - you have always officially passed.
For the two free courses we offer, you have 30 days to pass them - if you pass you keep them forever. After 30 days the course are $10.50 each.
If you buy a course within 30 days of sign up, then the free courses are yours forever and the 30-day time requirement goes away.