I think I only used about $0.03 last month. It says it resets in 16 days, so does that mean my $5 is still there regardless of the reset? Will it ever run out, or as long as I keep the usage under $5, will it refill?
But if you want to see how much you actually have left in your credit balance, go to Settings → Billing. There you can check your credit balance, billing history and change your usage limits.
Hopefully this clarifies it.
Edit: You can also see your credit balance in Home (dashboard) as well as your monthly budget and token usage details.