It is a common scenario that a customer will call because they did not receieved the license key (esp. for BUE) after renewing the maintenance and register it on the license portal.
After the registration, it says that Data not Available for the license key.
Maintenance are being renewed each year for free technical support assistance and free of charge upgrades.
Once the maintenance expired, a customer is still license to use the software however, he was unable to avail the other benefits.
How to get the license key:
Renewal Serial number is also for the maintenance and will not generate the license key of the product. One must process the upgrade in the license portal in order to do that.
One can also call customer service, to get the license key as well as the notification ID for the upgrade.
In addition to that, one can also process the license key directly on the license portal.