My billing is set up correctly and as I wrote previously the “Geocoding API” is one of the 4 APIs active on the API key I use. I already tried to: turn off/on all the APIs, regenerate the API key and even tried to create a new “Project” in the google console with a brand new API key and the same set of APIs attached to it.
So I am sure that the API key is ok, and the list of APIs provided by it includes “Geocoding API”.