Answer:
What gets sharper the more you use it?
I am one small little piece of paper yet sometimes hold lots of value. I am all you need to get in to big events but will cost you. I am an important part of travel. And if lost you're not coming.
I am what one cannot keep, two cannot hold, and three cannot destroy. What am I?
I can be repeated but rarely in the same way. I can't be changed but can be rewritten. I can be passed down but should not be forgotten.
My second is performed by my first. A thief by the marks of my whole might be caught. What am I?
Break me and I am better immediately set and harder to be broken again.
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic