The plugin will continue to work after your license expired as long as it works. If there is a breaking change due to WordPress code base update or deletion or if any third party code included in your plugin is not updated to meet the current web standards, it will stop working.
Basically, by using a plugin with an expired license, you assume the responsibility of maintaining the code base to keep the software in working condition. We always recommend keeping your software up to date to keep it in working condition at all times. If you do not renew your subscription and your license expires, you will not receive product support and software updates for your plugin any longer.