Thanks for the feedback Charles ... being able to restore a 3CX system quickly in the event of a hardware fault is very important to us - and therefore I will take this up with our local 3CX office in the UK to get their dictate on the matter.
Taking your Microsoft example - I accept that, but you can create a Ghost image of a hard drive (or even RAID1 mirror), and that will duplicate your Microsoft Operating System or Office license so that if your hard-drive fails, you still have an operational M'soft environment for your computer ... and - Strangely enough, the Microsoft Office license (not OEM though) will actually allow dual install of Office on a user's desk and laptop PC's - as the theory is that you'll be using one or the other.
It's quite strange that the standard 3CX backup application will create a copy of your system complete with license details (i.e. you don't need to re-input the license key into a restored 3CX system) - so technically, if I'm holding e.g. monthly backups of my system, am I violating the license because each backup contains the license key??? i.e. I have more than one copy etc. ...
What you can do, and what you are allowed to do - may be two different things of course. Licensing is a minefield - and backup is important - so I do want to take this further with 3CX ...