Tasks can be given due dates (expiry dates).
Setting the due date
Open the Tasks Popup, and hover over the task you want to change:
Choose Edit task to edit the task:
Select the date a the bottom to display the date picker:
Once you're done, choose Update to save the changes.
The due date will be shown alongside the task:
Removing the due date
From the Edit task screen, delete the date and then choose Update.
Notifications and reporting
Depending on App configuration (see below) anyone assigned to the task, or watching the page will receive notifications to let them know of the changes.
Details of the changes will also be stored in the Activity Report - Content.