I'm wondering what is the limit of Bing Distance Matrix API. From the docs here said 2,500 origins-destination pairs. Is it the maximum request per single request or the cumulative monthly limit? Another thing that confused me is about their billable transaction. What is it about the billable transaction?
I did try reading the docs and implementing the API. I'm a little afraid to try a 50x50 matrix as I will get charged.
That limit is per request. There is no monthly limit.
Non-billable transactions are tracked, but don't count towards the free limits (or paid for transaction credits). Billable transactions eat up the free credits and potentially into purchases transaction credits, if you have any.
Note that with Bing maps you have to purchase transactions before you can use them. So, if you don't have a license today, you can at most only max out the free limits. Once you hit the free limits, the service will stop working for your account until you decide to get a paid license, or until a new year has come around. So, you don't need to worry about a surprise bill appearing in this case.
In Bing Maps, every 4 cells in a matrix (origin/destination pair) generates 1 transaction. So, a 50x50 matrix would have 2,500 cells, and thus use 625 transactions. The Bing Maps free limits is 125,000 transactions a year. So, you could in theory run request a 50x50 matrix every other day and stay under the free yearly limit.