While it’s theoretically possible to continue using the platform after this date, it would leave your site open to security vulnerabilities and a system that will degrade over time.
Released in 2013, Umbraco 7 will be ten years old by the time it reaches EOL. It’s also more than 4 years since Umbraco 7 had any updates other than security patching - between HQ and the open source community, that’s a lot of years of bug fixes and new features you’re missing out on.
With typical builds taking several months from conception to public release, now is definitely the time to get your Umbraco 7 site updated