Works at an enterprise level (e.g. exchange rate providers) but would be a bad fit for a B2C product. Managing customer expectations on api key usage (esp. if

Works at an enterprise level (e.g. exchange rate providers) but would be a bad fit for a B2C product. Managing customer expectations on api key usage (esp. if that key is publicly visible e.g. URL parameter vs. HTTP header) is not worth it unless you have higher-priced products. Also api keys would mean you might have to prevent re-selling, etc. Furthermore, they could still analyze api key usage to get the same historical data on you as if you logged in.