Time

is fluid and perception of its passing is definitely related to age. As I've aged time  passes faster and faster, particularly when the events it encompasses are enjoyable! Unfortunately it seems to slow down and really drag by when those events are unpleasant. I would say I have had a very fortunate life and am blessed with so much of that life falling into the joyous category- giving me such a wealth of wonderful memories. Maybe that's why many older people experience short term memory loss? Could it be that our brains prefer to focus on a store of great experiences, friendships, and loves?
As for me, I've still got both long term and  short  term memories in plenty- although I do sometimes put my empty coffee cup in the refrigerator!