Load Balancer 500,000 first requests clarification

Hi everyone,

My question is fairly simple, yet when I searched I kept finding people asking about entire plan calculations.

I want to ask only about this specific parameter:

First 500k requests are free, is that a one time thing, or is this 500k free requests per month?
Then after those first 500k you pay 50cents per 500k, is what I get.

Thank you for any help!