Metered usage for the caller's customer over a rolling window -- window is hours (default 24). Aggregates across every key the customer holds, not just the one presented on this call.

keys[] splits those same totals per key, so a customer holding one key per environment (or per client) can attribute its spend. It lists the keys with at least one metered event in the window, ascending by key_id; each of the five totals sums across keys[] to the customer-level number printed beside it.