Answer:
Marking mortal privation when firmly in place. An enduring summation inscribed in my face.
One simple click, one simple flash. A piece of memory, for years I'll last. What am I?
Although I may have eyes I cannot see. I have a round brown face with lots of acne.
Never ahead, ever behind, yet flying swiftly past; for a child, I last forever; for an adult, I'm gone too fast. What am I?
Take off my skin I won't cry but you will.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.