Yes the DSS professional version does retain the IP values and others as well. For the trial version make sure to save your settings in the GUI from the Location of MAINTENANCE -> miscellaneous -> Function: Save settings.
Hmm, I had the trial version of DSS for quite some time and as long as the trial runs, it always retained the given IP. The only times it "forgot" the assigned IP was when I started over and created a new volume, to do some further testing.
Plus, licensing the trial made it of course immediately stick. Nevertheless, downloading the settings from the Web-UI is of course always a good idea.
When I called in about the trial the first thing he said was it wouldn't save the IP on reboot. I've rebooted two or three times and it always goes back to the defualt 192.168.0.220 on eth0. I've done the save settings and it didn't help.
Now, that's funny, because I also rebooted my two servers several times, and the never lost their assigned IPs. I was even able to setup bonding that would survive a reboot.
This also made sense to me, since the config is stored on a partition on the first LV you create, at least this is how it seemed to me, since I was running from a Demo CD back then and you can't of course write any config information back to it.