Any authenticated endpoint is providing (in HTTP response headers) information about the current state of the limits associated with API Key. The number of requests available to execute is calculated from the last 24-hour usage using the rolling window method.
For example at the 2019-08-22 13:00 UTC value of the requests remaining (X-RateLimit-Remaining) will be equal to the allocated quota (X-RateLimit-Limit) decreased by the sum of the request costs (SUM(X-RateLimit-Request-Cost)) executed in the period 2019-08-21 13:00 UTC - 2019-08-22 13:00 UTC (last 24 hours).
A request is deemed to be a single one if the limit query parameter on the endpoint isn’t available, or isn’t used. Otherwise — if the limit query parameter is available and is used — then each of the 100 data points returned in the response is counted as one request. If the endpoint didn’t have the limit parameter according to our documentation or it’s not stated otherwise then all successful requests are counted as a one.
More information: https://docs.coinapi.io/#request-limits