Microsoft regularly releases updates for Microsoft 365 apps, including Word, Excel, PowerPoint, Outlook, Teams, OneNote, Visio, and more. These updates are governed by Microsoft’s Modern Lifecycle Policy; this means that the product will be supported as long as the customer meets the maintenance and system requirements for the product and is licensed to use the specified software. According to this policy, support for Microsoft 365 apps on the three legacy operating systems will end in June 2023.

Microsoft has issued a warning that from January 10, 2023, Microsoft 365 apps will completely stop being supported on Windows 7, Windows 8.1, and Windows Server 2008 R2.

Although Microsoft 365 apps on the above operating systems were no longer supported, they continued to receive security updates through the Extended Security Updates (ESU) program that some customers paid for. This program ends on January 10, 2023 for the three operating systems mentioned above, so support for Microsoft 365 apps on these systems will end on the same date. New installations will be blocked as well as losing access to security updates.

As expected, the only workaround is to immediately upgrade to a newer supported operating system. Microsoft encourages customers to review this support matrix to determine which operating system will best meet their support and compatibility needs. Source