The Google Distance API does not require an API key, but this is something that should be supported for business licenses and per-key quota limit tracking.

Here are the quota limits:

Users of the free API: 100 elements per query. 100 elements per 10 seconds. 2 500 elements per 24 hour period.

Maps for Business customers: 625 elements per query. 1 000 elements per 10 seconds. 100 000 elements per 24 hour period.

Read more: https://developers.google.com/maps/documentation/distancemat...