If you still can’t find your product key, contact the seller to ask for the link or receipt to be resent. Try logging into the site where you purchased Office to check your order details. If you didn’t get a receipt, check your junk mail folder. The product key should be in your email receipt.
I downloaded Office from an online store. Tip: If your copy of Office came with a PIN instead of a product key, go to and enter your PIN to get your product key.