End of Support (EOS) means Trend Micro stops giving updates and fixes for a certain version of a Trend Micro app or program. After this date, the app or program won't get any more updates, and Trend Micro will only help you move to the new version.
For example, if you have an old version of Trend Micro Maximum Security and it reaches EOS, it won't get updates to protect against new threats. You will need to switch to the new version to stay safe from new viruses.
It's important to know the EOS dates for your Trend Micro apps and programs. This way, you can make sure they are always up-to-date and protected. Using software that is no longer supported can make your devices unsafe.