Device-based Office 365 Activation has stopped working. Computers in Labs/Classrooms that are Device-based Activated are switching to User-based Activation. This will consume a users Office Activation. Users may need to free up a license by going to portal.office.com/account, clicking on Apps & Devices. Then, under the Office section, click on Devices to show all devices. Users can click Sign out next to devices to free up licenses.

Example:

Office 365 Sign Out