: Windows 7 reached its End of Life (EOL) on January 14, 2020. This means Microsoft no longer provides security patches or technical support for the OS, making it highly vulnerable to new exploits even with a "valid" key.
: If you absolutely must use Windows 7 for legacy software, look for reputable refurbished hardware sellers that include a legal Certificate of Authenticity (COA) sticker.
: Unofficial activation tools modify core system files. This can lead to frequent crashes, the "Blue Screen of Death" (BSOD), or an OS that eventually refuses to boot.