The version of Windows Server Evaluation Edition is available for download from the official Microsoft website and is designed to evaluate the possibilities. The version has full functionality and normally works during the trial period (180 days).

At the end of the evaluation period in the lower right corner of the screen. you will observe the message: “License has expired”. This will shut down the server and even if you turn on the server again, it will shut down after an hour.

Under the terms of the Microsoft License Agreement, after 180 days of the evaluation period, you must purchase a license or stop using the evaluation version of the operating system.

However, Microsoft provides for a reset of the evaluation period and allows you to continue to fully use Windows Server again for the next 180-day period.

To do this, you will need to run the command prompt as an administrator and run the command:

slmgr -rearm

Then restart the server.

Despite this trick, it is correct and not contrary to the Microsoft license terms to convert the evaluation version to the normal one. To do this, you will need to run the command prompt as an administrator and follow the instructions below.

First check that the Evaluation Edition is installed:

DISM /online /Get-CurrentEdition

See the list of available versions:

DISM /online /Get-TargetEditions

Depending on the result and output of the command, select an available target version of Windows Server and perform the upgrade using the public KMS key.
For Standard version:

DISM /online /Set-Edition:ServerStandard /productkey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX /accepteula

For Datacenter version:

DISM /online /Set-Edition:ServerDatacenter /productkey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX /accepteula

Then restart the server.