The volume configuration is stored on the first volume you created, so if you install the the DOM with the key, it should discover your current volume(s).

You should also make a copy of the configuration data via the WEB-UI which you can then re-import into the purchased version.

Even if that doesn't work, the only things that you will loose are some generall settings. I have gone through that a couple of times when I tried DSS from the Demo CD - didn't had a problem once.

Cheers,
budy