I think the key word here is "remember". What we know or think we know about the past is our own recollection based on our point of view and biases at the time the events took place, or when you recall them.  That's why if you ask two people to re-tell a certain event you'd get two different stories most of the time. And since the future is highly influenced by the past and present, and not only our own actions, but the collective actions of everyone (the butterfly effect) it is impossible to predict, since it could be changing as we speak ;-)

i think we remember and think of the future so we can enjoy life and be critical of the world around us and therefore affect change in it.