As indicated at https://shop.highsoft.com/highcharts/,
"If you are a non-profit company, or use our products for personal use, 
you may enjoy our software for free under a 
Creative Commons (CC) Attribution-NonCommercial licence",
which is linked to:
https://creativecommons.org/licenses/by-nc/3.0/

Also note the license statement we received from HighSoft AB located in the HighCharts directory

Also note chart credits must be displayed wherever the maps are used (on by default in our map, do not disable)