As expected, this option isn't cheap, and the price will double every year until the program expires in January 2023:
For Windows 7 Enterprise and Microsoft 365 customers, Microsoft will provide Windows 7 ESUs as an "add-on," according to information Microsoft seemingly shared with partners and its field sales people. Year one (January 2020 to 2021), that add-on will cost $25 per device for that set of users. Year two (January 2021 to 2022) that price goes up to $50 per device. And Year three (January 2022 to January 2023) it goes up to $100 per device. To qualify for this pricing tier, customers can be running Pro as long as they are considered "active customers" of Windows Enterprise in volume licensing.Large clients may be able to negotiate discounts based on volume.
For users who decide to stick with Windows 7 Pro rather than Windows 7 Enterprise, those ESU prices are significantly higher. Year one, Windows 7 ESUs will cost those Windows 7 Pro customers $50 per device; Year 2, $100 per device; and Year 3, $200 per device, according to information Microsoft seemingly shared with its partners and field sales people.