Question about custom font

[donni-h]

Hey you guys,
I want to make some nice code snippets with one of my favourite font Berkeley Mono.
The thing is, that this is a font for which you need to purchase a license, so I doubt that I can upload it to services such as carbon.
My question now is:
If I import this (or any other font) into carbon to get some beautiful snippets, do the files ever leave my PC? Or does everything happen locally? :)

Thank you in advance!