Microsoft has stated that Windows 7 support will end in January 2020 and customers are recommended to upgrade to Windows 10 for monthly security updates. Microsoft hasn’t officially revealed the prices for Extended Security Updates (ESU) program yet and this pricing may change in the future. For Enterprise customers, Microsoft is instead pricing it as a more affordable addon at $25/device for the year, $50 for the second year, and $100 for the third year. According to a statement from Microsoft, customers are advised to speak to their Microsoft account team for exact pricing.
Source: https://www.bleepingcomputer.com/news/microsoft/new-docs-show-pricing-for-windows-7-extended-security-updates/