I am assuming you are using avast! Professional (managed) on the clients?
Provided you get the licensing you need, and considering you have only 10 clients, you should only have to put the new license file on the server, and then I would personally go to the desktop and point the clients to the new license file. You may have to manually update the clients, but that can be automated, as well.
Remember that you will also receive a key for avast! Professional as part of the Standard Suite install, and will need to use that for version 4.8, as 5.0 uses a license file, as well, and does not (at this point) work with ADNM.
HTH