If you've recently renewed the maintenance period on your DDM license you will need to refresh the license for this to take effect.
With DDM versions 1.0.6 and earlier, the way to refresh the license is to deactivate and reactivate the license via the License Management tab whilst DDM is connected to the internet.
From the DDM 1.1.1 release, there is a Refresh button in the License Management page to make this a simpler task.
If you experience a problem during this process please contact support via the Contact Support page on the Audinate Support Portal.