my memories?

Why do we have memories? Why do we store and organize memories from our past, those that seem purely sentimental and those that have logical rational reasoning(like that time I learned not to touch fire)? I wonder this now because in my physiological psychology class we are going over memory. And one of the main things he mentioned was that there was no where in the brain that specifically stores memory, so where is it all? I know that the hippocampus is involved with consolidation but after that where and why. This is what I've been researching in my spare time. which me luck.