While Microsoft rarely sues individual home users for piracy, using a preactivated ISO violates the Microsoft Software License Terms. Furthermore, distributing these ISOs is a federal crime in many jurisdictions. If you are a business, using one could lead to audits, massive fines, and reputation damage.
A "Windows 10 Preactivated ISO" is a modified version of the Windows installation file that has been tampered with to bypass the standard activation process. While these files are often advertised as "free" or "cracked" versions of Windows 10, using them introduces significant security risks and legal issues. Security Risks Windows 10 Preactivated Iso