this is how licensing works with the console, with the enterprise console, SOA has a neat feature i will point at on the bottom of the explanation:
The console scans the network for client devices. It will put them in a container and assign a license to the computer, even if you dont want that computer to have a license.
At the moment of installation of the avast client from the console, the license is also installed on the computer (green icon).
When you remove the avast client from a computer, the license will still belong to the computer according to the console (black icon since there is no contact anymore). If you re-image the computer and install avast client again, the license is installed again (green icon).
If you will not redeploy the computer in the network (trash) then you have to manually delete the computer from the container in the console to regain the license for another computer.
If you run out of licenses then new computers found by the console will get a greyish icon with a key, meaning there are no licenses for that particular computer.
To solve licensing problems often administrators disable the automatic discovery task finding new computer on the network. This way they are more in control over which computer gets a license, they run the discovery task manually when they need to add computers or add them manually to the console.
That is how enterprise console works. SOA however has a special container called UNMANAGED (at least it had last time i checked it out more then a year ago). If you put a computer in that container, then it will not get a license assigned to it, this way you gain control over which computers get a license and which not, without disabling any tasks.
(I put up an RFC for this licensing behaviour in the enterprise console)