You will likely see your current computer listed twice. Deactivate both entries.
This is a safeguard mechanism used by software vendors to prevent a single license key from being used to spawn multiple active installations on the same hardware or virtual environment. While it often indicates a simple glitch, it can also point to deeper issues regarding machine identity (Hardware IDs) or license exhaustion. activation key has already been used on this instance
Open Command Prompt as Administrator and type slmgr.vbs /rearm . Restart your computer and try entering the key again. You will likely see your current computer listed twice