I intend to resell the keys that's why I bought 3.
What is OEM?
source:
http://www.ebay.co.uk/gds/What-is-OEM-and-how-the-keys-work-/10000000003810855/g.html"The term, OEM (original equipment manufacturer) refers to companies that make products for others to repackage and sell. Resellers buy OEM products in bulk, minus the costly retail packaging that comes with individually sold units. The product itself is essentially the same as its more expensive, retail-packaged sibling. OEM products are used in many industries, but are perhaps most prevalent in electronics. "
"These keys will work in general same as Retail or Upgrade keys and can be used only once. which is what you want if you are getting OEM software"