With the startup state setting you can control the state of your luminaire when it is turned on. As a default the Startup state is set to Default mode and that means that the luminaire will go to default mode after it has been turned on.
With the Last state mode the luminaire will remember the state it was in when the luminaire was turned off and it will go to the same state when turned on again. You can also set a minimum level for the Last state. This means that if the luminaire was at 0% when turned off it would still go to some minimum level after it is turned on again.
You can find the 'Last State' setting under Luminaire settings. Double tap on the Luminaire control and select 'Luminaire settings'