Canvas courses have "Terms" which give a default set of start and end dates to any course assigned. After the end of term, you can read but not edit the courses (i.e. contents, grades).
If the current term course site will need to be edited after the end of term, please visit Settings
of your course site, select Participation: Course
and specify a later date in End
field (see screen capture
If you are unable to set the end date, please contact us (firstname.lastname@example.org
or 3442-6727) for support.