Answer:
To unravel me you need a simple key, no key that was made by locksmith's hand. But a key that only I will understand.
The more of them you take, the more you leave behind. What are they?
Though I wander the earth, I am no longer here. I am pale and I chill everyone near. Who am I?
What has 3 feet but cannot walk?
What is the thing which, once poured out, cannot be gathered again?
Of these things - I have two. One for me - and one for you. And when you ask about the price, I simply smile and nod twice.