All our plans are on a prepaid basis and pricing is a fixed amount per-month or per-year. We do not have a pay-as-you-go model where billing is done for every 1000 requests consumed.
The free tier comes with a generous limit of 5000 requests/ day and 2 requests/ second. Our premium plans start at $49/ Month. You can view all our plans here: https://locationiq.com/pricing
Write to us at firstname.lastname@example.org if you require a custom plan with higher volumes!