Never tried to upgrade the various UTM databases on a fgt with an exp. license, but to manually upload updates is done via System->FortiGuard. In 6.0.x. most items are accessible via right-clicking on a dashboard widget. In this case, right-click on the Licenses widget and choose View details in System > FortiGuard.
NSE4/FMG-VM64/FortiAnalyzer-VM/6.0 (FWF30E/FW92D/FGT200D/FGT101E/FGT81E)/ FAP220B/221C