The massgravel Microsoft Activation Scripts (MAS) are a collection of scripts for activating Microsoft products using HWID, KMS38 or Online KMS activation methods, I have only used the HWID script method which activates with a digital license based on the VM's so-called hardware ID. I haven't tried activating a VirtualBox Win10 VM, but I have successfully activated VMware Workstation and Hyper-V Win10 VMs using the HWID script method of activation.
Cloning is usually done from within the VirtualBox system, both the old and new VM are present after the cloning process is complete. As all UIDs must be unique, the new VM simply cannot use the same ones. Best practice is getting the VM to the point in time you want it to be (by restoring that snapshot), then delete all snapshots. Finally, make a copy of the VM directory. Re-adding in general to a new VirtualBox (or one without that VM present). Note that re-adding the VM (Using Machine - Add...) to a VirtualBox with the same VM still present is impossible. No. Rearm method doesn't work for Windows 8 and higher. There is no 30 days grace period anymore. Just use KMS activation (KMS_VL_ALL). It's offline and can be used as often as you like. You can create a snapshot, test all you want, and finally, restore the VM to the Snapshot you made earlier. All changes made to the VM after the creation of the Snapshot will be gone.
Thanks for the ton of info that you have given. I suppose that your activated Windows is not the volume-licensed type?
You have given me tons of info and guidance and I really appreciate your taking the time and effort to do it.
Suppose I use massgravel's scripts to activate Windows on my computer. Some weeks or months later I reformat my HDD and reinstall Windows on the same computer. Can I just re-activate Windows with the generic product key that is widely available on the internet or must I use massgravel's tools again?
Check read me there. No need to run it again, only need to make sure generic retail/oem key is installed.
HwID is bound to the hardware; you can reformat and reinstall as often as you like, provided the hardware doesn't change (and it is the same Edition, e. g. Pro). The generic Retail key is already present upon install for all non-Volume ISOs from MS.