However before you get up in arms over this decision, this only applies to the standalone copy of Office 2019, as opposed to the version that will come with the Office 365 subscription. For those who aren’t subscribed and prefer one-off purchases, then you’ll want to make sure that your computer is running Windows 10.
We know that Microsoft has been making a huge push for users and companies to make the switch to Windows 10, but it is understandable that following the confusion that arose in Windows 8 that there might be some who are hesitant to upgrade. Plus there is also the issue of familiarity, habit, and comfort that might see some users choose to skip the upgrade.
In addition to this new requirement, Microsoft has also revealed that extended support for the perpetual version of Office 2019 will run for two years, down from five years previously. However mainstream support will remain the same at five years.