Go to Settings > Advanced Settings > Map Provider: now we support 2 map providers: Google Map and OpenStreetMap.org
If you use OpenStreetMap.org, you don't need to input any API key, it's free.
– Google Map API Key: Enter your Google API key to this field
From June 22, 2016 google no longer support key-less access (any request that not include an API key). That is reason why the map on your site is missed.This post, we will guide you “How to get Google API for site”?.