I am using Microsoft Bing Maps for my mobile app project. The API which I am using is REST-Imagery Metadata. It shows on my account that it is billable after 25 hits. 490 hits have already occured. If the API is billable, how the billing is happening and what is the criteria for payment? Someone please clarify in detail.
It's buried in the Terms of Service - but you still get a certain number of "billable" transactions for free provided you're making a mobile-app, even a commercial app, if it's available for a non-Microsoft mobile device platform (i.e. Android and iOS). I imagine because it's free advertising for Bing Maps when users would otherwise be using rivals Google Maps or Apple Maps respectively.
Source: https://www.microsoft.com/en-us/maps/product
(c) Limited website and mobile app use.
If you are using the Services in an Application for commercial, non-commercial (except for Education or Non-profit use) or government use under these TOU, without entering into Standard Terms, then your Application must be available on a website or a mobile app running in a non-Microsoft Windows operating system, and must not exceed (i) 125,000 cumulative Billable Transactions (which will be free of charge) as defined in the Documentation, per calendar year or (ii) 5 queries per second, calculated as the sum of client-side and server-side queries. If your use will exceed these limits, please contact us to license additional transactions
It looks like Microsoft will deactivate your account or block further requests once you hit that limit of 125,000 transactions/year and then you'll have to register for paid access and provide payment method details.