Maintenance plans do not have an end date, and therefore have an unlimited duration.
However, you can archive them, or pause them momentarily and restart them whenever you want.
When you pause a maintenance plan, all future occurrences are suspended, and disappear from your network's schedule, to avoid confusing them with tasks to be performed.
You can decide to start it again at any time by clicking on the same symbol used to pause it. The occurrences will then be created again according to the plan rules.
This operation can also be performed from the maintenance plan page.