A Historics query is charged at a rate of 125% of the DPU cost of an equivalent streaming query.
The DPU cost of an Historics query is returned after you hit the /historics/prepare endpoint. The Historic will cost this many DPUs regardless of how long it takes to run. License costs are computed according to the volume of interactions matched by the Historics query.
Please note that Historics billing is based on the timeframe you are running the query over, not how long it takes to execute.
All billing information can be found in our Understanding Billing documentation.