This unique number is required during the installation of Microsoft office os. In many ways, what you actually pay for when you legally purchase a copy of Microsoft Office is the product key (sometimes referred to as a CD key or key code, or incorrectly as the serial number.
Microsoft won’t provide code fixes to resolve non-security related problems.Microsoft won’t deliberately prevent you from connecting to the service, but the quality of your Office 365 experience may diminish over time.
