When you buy Notmad, they register your Nomad. So you can install it on any PC but you can only use 1 nomad with it per copy you purchased. I've put Notmad on all of my PCs, including at work, but they only work with my Nomad, nobody else's. You should keep a copy of your transaction ID because that's how they know it's you.
and, if you own multiple jb3's, you need to go 'universal'
from crimson:
Here's how we normally handle second activations. If
the other player is owned or primarily used by another
person, he/she must buy their own license.
We do make an exception for households. If the other
unit is for yourself, a spouse, or son or daughter, you
don't need to buy a second full license. You can get
coverage under the Universal Edition license.
To upgrade to Universal, log into your account on our
website and you'll see a link to the upgrade page.