The Windows Server operating systems are licensed in Cloud Servers according to the core license model.
The number of core licenses required is determined by the number of cores per server. You need one license per core. If you increase the number of cores used, you need additional licenses. The additional licenses are automatically invoiced.
For legal reasons, this also applies to Windows Server operating systems that you install using an ISO image and for which you use your own license key.
For servers created before November 30, 2016, a flat rate is charged for the Windows license. If you reinstall the operating system on these servers, the Windows license will then instead become licensed according to the core licensing model.