Two separate licenses of 1,600 and 200 were combined for a single license file of 1,800. I installed the new license file, but it did not update the license count as shown on the license page of the Notification Server Console (Configuration > Licensing > License Status). It still showed only 1,600 total nodes for all of the Solutions.
For Notification Server SP2, remove the licenses with the AexLicenseManger.exe then reinstall.
For Notification Server SP3, manually remove licenses. To do so without the license removal tool, you can perform the following steps:
If that doesn't resolve the problem then:
The correct number of license counts should now show up under the license page of the Notification Server console.
Notification Server 6.0.5287 (SP2), 6.0.6074 (SP3)