What version of SQL Server? In SQL Server 2005 and 2008, DISABLED is the normal setting. SQL Server 2005 and 2008 have no licence option at installation and it's not recorded anywhere in software. Licence is on paper only.
For 2000 there is a licence type that can be specified at startup. In that case I would guess that DISABLED means it wasn't specified or is not relevant (Developer Edition maybe?).