Large companies use KMS (Key Management Service) keys. These are not real product keys that you can reuse. If you see a KMS key, your Office 2021 is tied to a corporate server. You must contact your IT department.
For Office 2021 Retail:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\16.0\Registration
Look for a subkey with ProductName containing "Office 2021". The DigitalProductId value contains the key, but it's encoded — you'd need a decoder script (ProduKey does this automatically). ms office key finder 2021
✅ Always download from the official developer’s website (NirSoft, Belarc, Magical Jelly Bean).
✅ Upload the .exe to VirusTotal before running it.
✅ Run a full Windows Defender scan after use.
✅ Never share your recovered product key on forums or “validation” websites. Large companies use KMS (Key Management Service) keys
Go to the NirSoft website (search “NirSoft ProduKey”). Do not download key finders from CNET, SourceForge, or random ad-laden mirror sites. Use the official publisher’s site. Look for a subkey with ProductName containing "Office
Microsoft changed licensing for Office 2021:
This uses Windows Management Instrumentation (WMI) to query Office.