Microsoft had discontinued Windows 7 and Windows Server 2008 R2 on January 14, 2020. All SKUs no longer receive updates, except for those customers who purchased Extended Security Updates (ESU). The ESU offer has been available in the Volume Licensing Service Center (VLSC) since April 1, 2019. Microsoft sells ESU in specific 12-month periods, so it is the right moment to pay for the year two.
Microsoft noted that many organizations have already upgraded their machines to Windows 10, with some of them running Windows 7 in virtual machines, there are plenty of customers for whom ESU is a last resort.
Because ESU are available as separate SKUs for each of the years in which they are offered (2020, 2021, and 2022)—and because ESU can only be purchased in specific 12-month periods—customers need to purchase the second year of ESU coverage separately and activate a new key on each applicable device in order for your devices to continue receiving security updates in 2021. If an organization did not purchase the first year of ESU coverage, it will need to purchase both Year 1 and Year 2 ESU for the applicable Windows 7 or Windows Server devices before installing and activating the Year 2 MAK keys to receive updates.
Interested users can learn more details here.