Commentaire officiel
You can cache as many maps as you want. We just require that you get your own Mapbox account (free) to do so so it doesn't continually cost us money. The access token really has nothing to do with GIS and is a way for our app to be able to use your account's data while you are using it.
Please refer to the following article:
http://support.dronesmadeeasy.com/hc/en-us/articles/207716853-MapBox-ID-and-MapBox-Access-Token
From the article:
"Since we have to pay for every single map load we show and want to keep the cost of the app below $20, we allow users to save 10 missions using our default Mapbox access credentials. Beyond those initial sample cached basemaps, we ask that if users wish to continue using that feature they will need to sign up for their own Mapbox account to continue caching map tiles. Missions can be saved without the need to download cached basemaps if they will have data service in the field."