Microsoft Product Key Activation

Hello,

I'm trying to activate my excell program. Have been using it in the trial version option but have run out of uses. When I bought my computer, I was told it came with MICROSOFT Excell but never bothered to activate the code. Now when I try, I'm told that my code is invalid. The product code on the bottom of my laptop is: ZVW3Y-MQPXJ-D24V2-8XJ7R-GYMHP.

Please provide me with a valid code or tell me how to get one.

Thanks,
Pete Watson