I can also confirm that this energy meter has its own backup battery. It can therefore store all values for approx. 3 months without mains voltage. :)

Romulus17's answer is not correct. It has a backup battery that stores the values for about 3 months without mains voltage, according to the instructions.

Only as long as it is plugged into the socket and voltage is applied or until you press the reset button. In that sense, it has no memory.