The .service file was used when aw-qt didn’t exist so simply autostarting aw-qt when you start your desktop is currently the recommended way to do it.
However if you would still like to run it as a service, it’s possible. Previously we ran aw-server in a service file (always, no matter if your desktop was running or not) and then autostarting aw-wathcer-afk and aw-watcher-window when starting your desktop session. The issue with this however is that if any of the watchers crashes you will not be notified and it will not restart, however that should not happen anyway so it hopefully shouldn’t be an issue. It would be cool if systemd could be aware when a desktop session is started and then start the watchers, but as far as I’m aware that is not possible but I might be wrong.