To revoke unused app licenses assigned to a user or a device, you can Block the bundle assignment, Remove the bundle assignment, or Disable the bundle. When any one these actions are performed and the device syncs with the ZENworks Server, an uninstall command is sent to the device and the app license is revoked. For details on the Block, Remove and Disable options, see Bundle Tasks in ZENworks Software Distribution Reference.
If the device cannot sync with the ZENworks Server, then you can click on the Apple VPP License Summary page. This option can be used to revoke licenses in the following scenarios:
Mobile device management on the device is disabled.
The device is in a Retired or Wipe Pending state. In case of a device assignment, all apps assigned to the device are to be revoked. In case of a user assignment, if the device is the last device associated with the user, then the app licenses are to be revoked from the user.
Bundle assignment is removed.
User does not exist anymore.
As stated earlier, unused app licenses are revoked when the device syncs with the ZENworks Server. Also, every two hours ZENworks automatically revokes unused licenses from devices that cannot sync with the ZENworks Server. However, if you do not want to wait for the device to sync or for ZENworks to automatically revoke licenses, then clicking helps in revoking licenses instantaneously.