CUIT's current response to this question is:
"Students and alumni do not lose access to courses in Courseworks. Current students and alumni see all classes [in which they are/were officially registered]. If a student drops a course, Courseworks removes them from that class within 24 hours.
Students who leave the university without becoming alumni lose access to Courseworks when their general UNI access expires. This happens when the registrar removes them from current enrollment lists, typically two semesters after they last registered for a course. Note that they are still listed in the class, but they cannot login to Courseworks."