How many activations are allowed on a virtual machine?

Hi,

I'm thinking of purchasing a Standalone Named User Individual licence. However I will be installing on a Virtual Machine (VirtualBox). If that VM is destroyed and recreated would another install count as a machine from my possible number of activations? ie. If the machine was destroyed four times would I need a new licence?

Is it possible to deactivate the install after the machine has been destroyed? Can deactivation been done via the MathWorks account or does it have to be done on the physical (/virtual) machine?