Resolution
Sitebuilder license number can be found at the Server->License Management page in the Sitebuilder CP, see the "License key number" field. It looks like "SB.00XXXXXX.000X".If the Sitebuilder Control Panel is not accessible, the license number can be found from the "sitebuilder3" database. Login to the Sitebuilder server via SSH.Login to MySQL with administrator account and run the query:
mysql> select l.name from license_key l right join config_param c on c.value=l.id where c.name="active_license_key";
+------------------+
| name |
+------------------+
| SB.00000000.0000 |
+------------------+