Hello Nniltin333
To upgrade your Windows Server from the trial version to a full version, you will need to purchase a valid license key. You can purchase a license key from Microsoft or from a Microsoft authorized reseller.
The number of license keys you need to purchase will depend on the number of physical processors and the number of virtual machines running on your server.
You can purchase a license key for Windows Server from the Microsoft Store or from a Microsoft authorized reseller. Once you have the license key, you can activate it by going to the "Settings" app, selecting "Update & Security," and then selecting "Activation." From there, you can enter the license key and activate your copy of Windows Server.
Best Regards,
Hania Lian