Google Maps API Key (v3)
The API Key enables monitoring of the Google Maps API.
And for some sites also need Google Places API Web Service enabled to work. The Google Places API Web Service does not work with an Android or iOS restricted API key.
So you have to create new key if or remove restricted access of existing key to work it properly.
You can learn more about the Google Places API Web Service here https://developers.google.com/places/web-service/get-api-key