Google Maps API

Hi,
i have problems with google mas since three weeks now.
I registered new in google cloud platform for the new API key. And Confirm my bank account.
And i registered there the different URLs of my client websites where google maps is integrated, but it is still not working.
I don’t find where to insert my API key. In my Highend options there is only Maps Configuration but not for the API key.
Im using WordPress 4.9.8 and HB Highend-Theme Child Theme Version 1.0.0, Highend 3.1

I saw that a few people have problems now with the new Google API Keys, can you help me?
Thanxs herman