How do I confirm that a licence bought second hand is genuine?

[Richard Ford]

I have recently bought Office 97 second hand across e-bay. In future I may
wish to do the same for other/more recent versions of Microsoft software and
want to know whether it is possible confirm that what I'm buying is not an
illegal copy.

 

[garfield-n-odie]

See http://www.microsoft.com/resources/howtotell/ww/office.mspx .