Windows Server you got from Microsoft homepage is evaluation version and it has been attached 180-day trial license. As a result, you can not install another key on your machine, in this case, KMS client key. For that reason, today I will show you how to convert the evaluation version to the retail one. Convert Windows Server Evaluation to Retail version Determine your edition of Windows you are using. Open the command prompt  as administrator then execute this command. dism /online /get-currentedition In this case, I am using Windows Server 2019 Standard Evaluation. List the editions that you can convert your one to. Run the following command. dism /online /get-targeteditions As you can see, I can convert my OS to the retail version of the Standard edition or upgrade it to the Datacenter one. Convert your Windows to the edition you want. Execute the command below to start a conversion process. dism /online /set-edition:<-Edition-> /productkey:X-X-X-X-X /acce...