There is something special about impermanence. It puts value into every moment and makes these moments very precious, because they become unique and irreplaceable. And because of this, we learn to enjoy every moment more thoroughly and learn not to take things for granted. However, just because certain moments/things have gone and will not happen again, it does not mean that they are erased. They have happened and will always have happened. And I think that this is the true value of our treasured moments, which we will not be able to appreciate without impermanence. The most precious moments of my life only lasted 2 seconds, but they will sustain me for the rest of my life, if you get what I mean.