Setting Automatic Expiration
On whichever resource level (a file, a folder, a section or the whole account) and with whichever permissions (previewer, viewer, editor), you can set the access to expire at the time you choose.
Just start sharing a resource, by clicking on the Sharing icon and a share window appears. Choose whome to share to and toggle on ‘Expiration’.
Choose a date and time and click ‘Share’.
To modify an exisiting expiration, open the sharing window again and click on the blue clock icon next to a person or a group name to modify the time or click ‘Clear’ in the calendar view to remove the access expiration from that person or group.