Hello Systeembeheer3
If the license for your physical server is a retail license, then you can transfer it to a virtual machine as long as you remove the license from the physical server.
In the case of MAK activation, a MAK Key can activate a server a certain number of times. You can view the remaining number of times in the Volume Licensing Service Center (microsoft.com)
In the case of KMS activation, the KMS server must have sufficient activation count and have one KMS host.
However, if the license is an OEM license, it is tied to the hardware of the physical server and cannot be transferred to a virtual machine. In this case, you would need to purchase a new license for the virtual machine.
Please Note:It is important to review the licensing terms and conditions for your specific license to ensure compliance.
More details please refer to this link:
Frequently Asked Questions for product keys. | Microsoft Learn
Best Regards,
Hania Lian