You do not consciously use your full mind when you do things.
The mind is full of random thoughts which keep on intruding and thus cause
you to forget things. When you consciously, in each moment of time, use your full mind and do or say anything then it gets etched on to the brain and can never be forgotten.
There are some who need to write down everything or depend on electronic equipment. You do not need to do this.

Let us see what this Mindfulness is. It is that mode of the mind that is
not filled with random thoughts. When you sit for meditation you will notice how many random thoughts keep on intruding and taking you away from the object of your meditation.

Mindfulness means a mind full of conscious thoughts, focused and chosen.
You need to learn to focus and hold on to the chosen thought.

The following is a very good exercise in helping you attain mindfulness in all that you do so that you need not forget anything.

Watch your breath. Visualize a tiny leaf in front of you. Now practice breathing in and out with the leaf. As you breathe in visualize the life being drawn towards you and as you
exhale visualize it moving away from you. Watch your breath coming in and going out with the aid of the leaf's movement. Practice this exercise daily and your breathing will improve because now you will be breathing consciously and fully - in mindfulness. [Your mind is full of only conscious breathing and so no random thought can intrude].

You do not live in the present moment. A moment is all that you have. How
many times you have heard this. When you learn to consciously live in a
moment it means that in each moment you are fully aware, conscious of what
you are doing. For e.g. after this class is over, try and notice when you
get up and put the chairs away. Are you doing it consciously? Are you aware that  ‘here I am picking up this chair and putting it in its place’? If you do that
then you will not forget where you put the chair. Even after an hour you
will remember that yes, I put it in this particular place. This is because you chose to consciously focus your mind on the one action you were doing in that one moment. If you use this method of putting away things consciously and with choice and full attention, why would you forget keys or files?

Your environment is a very strong puppeteer. The environment pulls you and you dance accordingly. You are not in control. Your environment is controlling you. You like to control others and everything around you but you give away your power to others to control you. Why? You are in control, you choose what to think, say or do.

When you consciously live in the moment and choose your thoughts, words or action you are in control. You are in MINDFULNESS.

You only have one moment of time which is truly yours. Be fully in that moment. Then with the practice of this living in the moment, slowly all your random thoughts will get erased and your mind will become clearer. You will be in control of yourself.