When you open the Windows 2000 Licensing tool and press New License, the License Mode option is set to Per Seat and you can't change it? If you add licenses, additional clients may not be able to connect to the Windows 2000 server?
If you ever added per-seat licenses to a server that was configured Per Server, this problem will occur.
To fix the problem:
1. Open the Licensing tool.
2. Select the Server Browser tab.
3. Select the server you want to add licenses to. The list is organized by domain.
4. Under the appropriate server, Double-click Windows Server.
5. In the Per Server section, press Add licenses.
6. In the New Client Access License box, enter the number of additional licenses you are adding.
7. Press OK.