From SQL Server 2008, the fulltext index is always enable on the user database and can not be disable. However, to make it effective, we must create the fulltext index.
Also, the MSSQLFDLauncher service must be installed on the host. The service is instance specific. The actual executable is fdlauncher.exe.
We can user SERVERPROPERTY to determine whether the full text search feature is install for the SQL Server.