Train your short-term remembrance. The duration of short-term remembrance seems to be between 15 and 30 seconds, and the capacity about 7 items. Short-term remembrance is improvable and you can get better by remembering numbers in order.

There are cards on the board and in each card has a number on it. You need to open them in order, to finish the level. If the number you opened is not in correct order it will be closed and you need to open it again when the right time comes.