In the Command prompt window on an installed GN4 server, switch to the folder where srv4 resides and then execute:
srv4 license -show
This identifies your GUID. Mail it to the licenses@teradp.com together with the request of the wanted number of specified functionalities.
When you receive the information about license upgrade, perform the step as explained in Sync a license with the GN4 license server.
See also
Sync a license with the GN4 license server
Import a license when supplied in a file