How to find out what providers need an API Key

[newb with dumb questions sry]

Sorry for the probably dumb question :§

How do I find out what providers need an API key? Or to ask specifically does BVG and VBB (Berlin and Brandenburg) require an Api key?

Im asking because I am using a plugin for an android launcher thats a thin wrapper around this but can only query providers that dont use an api key

again sorry for uninformed noob question but I really just dont know how to find it out on my own

thanks in advance for any tips