HPM stands for 'Hits Per Minute'.
This is the primary metric that we use to distinguish between our different licence tiers.
Our paid licence tiers never have any daily or monthly usage caps, and we never charge for usage (e.g 'per element'). Instead, we simply set a cap on the number of hits you can make to the API in any given minute.
1 Hit is defined as:
1 Isochrone
OR
1 Route
OR
1 Matrix (1-to-many or many-to-1)
So with a limit of 60 HPM you could create 60 isochrones, or 60 routes, or 60 matrices every minute.
Requests to the Geocoding API or Map Tiles API do not count as hits. There is no limit placed on these endpoints for paid licence plans.