Office 365 - Microsoft Office 2013 Path to retirement
Which version of Office 2013 is affected?
All versions of Office 2013 are affected. Note: Users upgrading from Office 2013 to Office 2016 should have no problems due to system requirements.
Should I upgrade to Office 2016?
Yes. The newest version provides a better user experience (including enhanced features), receives the latest security updates and enhancements.
What happens if I do not upgrade
Office will no longer receive the critical updates (by Feb. 2017). Note: Microsoft official date for end of support is April, 2018.