How to activate Microsoft Office 365 for free legally? or how to use the serial key or serial number? you can read this article. Like the predecessor of Microsoft Office product, a product key card might also contain bar codes. The other groups of letters and numbers, but the product key or serial number, a serial key will always be shown in the format XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. Microsoft Office 365 has many models including Microsoft 365 Personal, Microsoft 365 Family, Microsoft 365 Apps for business, Microsoft 365 Business Standard. This is a simple method and work on Microsoft Office 365 product key or activation key 32 and 64 bit for free.