The way you can find your ms office 2016 serial key [/b]depends on how you got Office 2016, this can be pre installed on your device, from an online store, from a physical store, got through a partner, got as a student from school. The source from where you have got your office 2016 is your source too from where you will get your ms office 2016 key.

If you are unable to find your [b]Microsoft office 2016 product key, or you want to reinstall your office, if you associated a Microsoft account with Office, you don’t need a product key for MS office 2016; If Office is prompting you for an ms office 2016 serial key, you can enter your Microsoft account instead. Try selecting the Sign in with an active account instead link in the Enter your ms office 2016 key dialog box and sign in with the Microsoft account that you associated with Office.

you can download Microsoft Office 2016 with Product Keys from link given below.

https://getbaseapp.com/microsoft-office-2016-product-key/405/