We can call our memories the profit we receive on the investment made or they can prove to be the interest we have to pay out of our pockets for the future. It depends on the kind of the crop we sow. After all, as we sow so shall we reap (as goes the old English adage).
Memories have the strength and ability to change our lives. Some memories tend to fade but some just hang out there, flashing in front of the eyes of our mind every now and then. To some extent we can control our memory - in the sense that we forgot only those things that we want to forget. Moreover, this forgetting is a sort of boon for the human mind. If our little mind were to remember all those things, we would soon be tired of the lingering thoughts. It is only because of this forgetting that life goes on and is as beautiful as it ever was, sans those painful and the remorseful memories - those that we always wanted to get rid off.