With the new version 10 license management came authorizations & deauthorizations. When users want to renew licenses within the License Server Administrator, they have to authorize licenses using new EFL authorization code before old licenses expire. Old expired licenses remain in the Availability list. This caused several issues which were resolved by the SP2, but still those licenses are present there. To remove them, the only workaround is to deathorize new licenses, delete the Flexnet folder and reauthorize new licenses again. This is not very user friendly and I am looking forward to having the Update License button again in the ArcGIS License Manager as was in 9.x version.