Hi Jaroslaw Rozniecki
to extend update support for Windows Server 2012 R2, you will need to purchase Extended Security Updates (ESUs) from Microsoft. ESUs provide security updates for eligible products beyond the end of support date.
To purchase ESUs, you will need to have an active Software Assurance (SA) or subscription license for the product you want to extend. Once you have an active SA or subscription license, you can purchase ESUs through your Microsoft account representative or partner.
After purchasing ESUs, you will need to install the latest servicing stack update and the ESU product key on your Windows Server 2012 R2 devices.
For more information about how to get ESUs, please see How to get Extended Security Updates (ESU) for Windows Server 2008, 2008 R2, 2012, and 2012 R2 | Microsoft Learn.
Hope it helps.
Regards,
Lei