If you have saved your latest temperature on your thermometer (you can read about how to do this here), the saved temperature is shown for a couple of seconds when you turn the thermometer back on.
Your thermometer will then show a reloading value of 37.00°C (± 0.01°C) or 98.60°F (± 0.02°F) as it gets ready to measure again.
You can view your saved temperature as many times as you want, as long as you turn the thermometer off before it flashes onward to start measuring again.
Please make sure that you don't miss the saved temperature and accidentally enter the thermometer’s reloading value into the app, as it is not your temperature. Remember, your saved temperature will show with a small “M” symbol (M=memory).