Here’s a useful, neutral review of HEU KMS Activator v42.0.1 (likely what you meant by "v4201") for Windows and MS Office.

MS Office Support: Compatible with versions ranging from Office 2010 to Office 2024 and Office 365.

Office Tools: Includes capabilities to convert Office editions (e.g., Retail to Volume), uninstall Office completely, and bypass "piracy" pop-up notifications.

Local Server Emulation: Instead of connecting to a remote server, it creates a virtual KMS server directly on your PC to authorize the software.