[bredo]

At March 22. I will give you the answer to if you have to buy it once, or if it is in some way linked to the hardware.
I will anyway try to upgrade both my 11 Racks with only buying the upgrade once.
I'll guess this will work fine, as it would cost Avid more to make solutions to hinder this. There are not many enough that owns two units to justify the hassle for them (I think).