If power is cut the machine will surely turn off, but when power is re-established the machine will not boot up. Rather, machines with soft power are turned on via an ADB signal that is sent from the keyboard when the power on key is pressed. Because the PowerKey plugs into the ADB port of the Mac it is able to send this signal and boot a machine even if it is a soft power Mac. The hardware setup dialog also offers an opportunity to disable the buttons on the PowerKey unit itself, which might prevent a user from inadvertently switching power on or off to an outlet by bumping a switch or dropping something onto the PowerKey. The PowerKey software is essentially an event editor.
Events can be one-time events, repeating or scheduled daily, weekly, monthly, etc.
Events may also be qualified. They may be allowed to run during certain hours of the day, days of the week or days of the month, but not at other times. Clearly the PowerKey is powerful and robust. However, the manual is outstanding and it is important to read. It offers some vital information.