memories........

memories ~ an event or experience that one remembers from the past.
does memories fade with time? even those with memorable times when u spent with someone special?
for a long time now, i am afraid that the good memories i had would disappear or fade away. and it seems to me now that it had happened. the memories i cherished most seems to have disappeared frm my brain. is it due to old age or juz because i have already used up all my "hard disk" space?