Hi @Panagiotis Papaioannou ,
KMS host keys will activate up to 10 times on six different computers. If more activations are necessary, contact the Microsoft Activation Call Center:
https://www.microsoft.com/licensing/resources/vol/numbers.mspx
Hope the information is helpful.
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.