To check if your Windows or Office is activated using KMS, you can use the Command Prompt. Open Command Prompt as an administrator and type the command `slmgr /xpr`. If your product is activated with KMS, it will indicate the expiration date of the activation. You can also go to the activation settings in Windows or Office to see the activation status. If you notice that it’s activated but with a temporary license, it may indicate KMS activation.