Hello DK

Your product key is 25 characters and is found in different locations depending on how you acquired your Office product.

If you purchased Office on a traditional disc the product key should be located inside the package on a label on the card opposite the disc holder on the left side of the DVD case.

If you purchased an Office product key card the product key should be located inside the package on a label on the left side of the case.

If the product key is not inside the package, please review the instructions in the package.

If you purchased and downloaded Office online the product key should be on the confirmation page and/or email that was sent to you when you downloaded the software.

If you purchased a new computer with Office preloaded the manufacturer of your computer should have included either media or a Microsoft Product Identifier card in the box that has the product key. The product key is located on the Certificate of Authenticity.

hope u like the answer 

have a charming day :-)