Thanks for using JustAnswer.com I am Cris. Was the product purchased from the Microsoft store?
Hi this is Stefan. I will be glad to help. For Windows computers there are key finders that search your PC for your product keys. I do not generally work on Apple products but I have included a key finder you can put on your old laptop that will find all your old key. http://www.macupdate.com/app/mac/36175/mac-product-key-finder
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Just checking back to make sure everything went ok. Please let me know if you need further assistance.