i just bought a new computer Mac and copied all my files over from the old computer.  When I opened Excel for the first time, I input my Product Key and it worked no problem.  Now I have opened Outlook and it is asking me again for the Product Key.  When I enter it, it says my product key is not valid.  I'm wondering why it is prompting for a product key at all since I have already activated it on this computer and then, why it isn't working when I do enter it.

I have Microsoft Office 2011 (no Office 365).

Thanks!