What happens if you don't accept rewards and transfer to balance?

I'm noticing something fairly new to Steemit. In my wallet, a button that says something like "Accept rewards and transfer to balance" pops up when its time to receive the author/curator rewards for a post.

I understand what that means and what happens when I press it. What I'm wondering is what happens if I don't press it? Do the "rewards" go away?

Any help is appreciated!