The iPhone allows users to manage and close Apps to save on processing power and battery life. You can access this feature by double clicking the Home button.
Because of how iOS7 is designed, Trac-King must be open (or operating in the background) to track your country location, so please don't close it!
But, don't worry, Trac-King uses very little processing power, it is designed to run in the background and does not rely on GPS so it won't run your battery down.
Just leave it running to count all your days and nights year round.