“Unlicensed” means it got the key, but is unable to activate it. In our case it was internet access blocked.
We had to enter the ESU Installation ID into a Microsoft activation site (link is dead now), and get a resulting Activation code. We then entered the following (for 2008):
“slmgr /atp ~activation code~ 553673ed-6ddf-419c-a153-b760283472fd”
That changed the license status to “Licensed”, and the servers became relevant to patches in Bigfix.