I have a Sony Vaio VPCEH2F1E/B.  Is my Microsoft office 2010 just a trial package or do I have this basic version built in for use whenever?  It opened fine for the first few weeks but now won't, its trying to make me enter the 25 digit product ket.  I've done this using the 25 digit number on the label on back of the lap top but am getting "this is not a valid product key number" message.  Please advise.

Thank you.