Windows 7 will reach end of support (EoS) on January 14, 2020. Microsoft introduced a paid-for service called Extended Security Updates (ESU) that allows licensed users to continue to receive security updates. Some devices, such as voting systems, can get this service for free for a limited time. Other business users who have a volume licensing agreement would need to purchase a license for $25 to $200 per device. BypassESU bypasses the ESU license checks so that users can get the updates for free.
Source: https://www.bleepingcomputer.com/news/microsoft/tool-illegally-enables-windows-7-extended-security-updates/