I’ve seen several posts like this one that reiterate that ESRI has announced that: ‘As of the end of January, ArcGIS Online basemaps published and hosted by Esri are now freely available to all users regardless of commercial, noncommercial, internal, or external use. This means that you no longer have to pay a subscription fee for including ArcGIS Online basemaps in your commercial-use web applications. Basemaps included in this new business model are World Imagery Map, World Street Map, World Topographic Map, USA Topographic Maps, and DeLorme World Basemap.