I'm sorry, there is nothing WE can do about your product key. If MS Office came preinstalled, there will be information that came with it regarding the product key. If you bought it yourself, there will either be a card in the box (if it came that way), or you would have an email from Microsoft (if you bought it online).
HP keeps no record of product keys for add-ons, so they can not provide you this information.
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