Ecdysis (molting of the older cuticle)
A snake sheds it's skin because it is worn out from crawling on the ground or because the skin becomes too tight and needs room to grow. This also helps the snake get rid of external parasites. Before it molts, the snake stops eating and then it's eyes become cloudy, the skin dull and lighter. Animals that grow during their entire lifespan discard from time to time the outer layer of the cuticle (a Serbian word for a snakes skin is "zmijska košuljica" (the snakes shirt).
For a promise kept, the photographs a small gesture of gratitude. And also as a fragment of an attempt to return a debt, and a great responsibility that was let loose from it's hiding place in that same package.