Do i need coa when buying windows 7 software?

i have vista on my pc and want to upgrade to windows 7. ebay has listings for keys and download links claiming the keys to be authentic, genuine, pass wga etc.... however other listings contain the actual software with coa (certificate of authenticity) So... do i actually need to own the coa?

I guess coa is to prove the authenticity of the software they sell, but I personally wouldn't buy a windows license from e-bay. The best place to buy Microsoft products is this:


Microsoft Store Home


Microsoft MVP
Staff member
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Microsoft MVP
I'd avoid buying keys and download links - almost guarantee that sooner or later you'll have problems.

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