The interface will continue to give an ignition feed to the radio until the key is turned back to the off position. This interface also provides an illumination output to dim the radio when the headlights are on and includes a break out wire to power an amplified antenna if the vehicle is fitted with one.
It saves you having to do wiring to get a live to the stereo. But as it’s only live when the ignition is on. Each time you turn the car off. The radio forgets the country, time and any Bluetooth connections. So each time you start the car you have to set these up. Which is very annoying.