The current version of Parallels uses the stable build of Windows 11 for ARM.
Once you've installed Windows, it's possible to pay for and license Windows directly from Microsoft via the Windows Store app. There might be a brief period where you're technically unlicensed (not sure what the exact verbiage is in the current Windows EULA about trial/grace periods), but the end result is a properly-licensed Windows 11 install.
Once you've installed Windows, it's possible to pay for and license Windows directly from Microsoft via the Windows Store app. There might be a brief period where you're technically unlicensed (not sure what the exact verbiage is in the current Windows EULA about trial/grace periods), but the end result is a properly-licensed Windows 11 install.