Hi, JohnHi George,
If this was a commercial license (i.e perpetual with expired maintenance) then it is normal to have the message "feature is disabled in currently activated licenseBLF" and this would explain why the BLF stopped working.
You can PM me with your key if you want and I can check a couple of things from here.
Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.