ArcGIS Online basemaps published and hosted by Esri are available at no cost for internal or external use if you are using Esri software, have an ArcGIS Online subscription, or have a developer account.
Q: Is there any cap on usage?
A: Yes. If you have an ArcGIS Online subscription, ArcGIS Desktop, or ArcGIS Enterprise, you are limited to 50,000,000 transactions in a twelve month
period. A transaction is defined as 8 tile requests which equates to
400,000,000 tile requests per year or slightly more than 1,000,000 tile
requests per day.
If you have a developer account, you are limited to 1,000,000 transactions per month.
Q: How can I estimate if I might reach the transaction limit?
A: To help determine whether you may qualify as a high volume user, the following calculation can be made:
Multiply the number of expected users per day times the number of times you expect they might pan or zoom the map. If you think you will have 200 visitors, and each visitor will pan or zoom 10 times, a ballpark number of transactions is 2,000 (200 visits times 10 pan/zooms) per day.
Q: What do I do if I think my applications might reach the cap?
A: Contact your local Esri office.
In the United States, you can also call 800-447-9778.