This module provides the ability to convert address field values into a set of coordinates that are stored with the entity. This enables the content to be found in search based on location.

OpenStreetMap

By default this module uses the OpenStreetMap API. It is not needed to enter an API key.

You can find the usage policy here: https://wiki.openstreetmap.org/wiki/API_usage_policy

Google Maps API Key

Optionally you can use the Google Maps API to transform address strings into lattitude/longtitude pairs. For all server side requests no Google Maps API key is needed, however, rate limiting may apply. For the client side requests which include the proximity filter and map blocks, a valid maps API key must be entered on the geolocation's configuration page.

You can generate a key here: https://console.cloud.google.com/google/maps-apis/api-list?project=social-local-171213&organizationId=841499249988

Configuring your own Address fields to store geolocation data

You can simply enable the field_ui module

See step "Geocoding results from Address field": https://www.drupal.org/docs/8/modules/geolocation-field/configuring-integration-between-geolocation-and-address-field

And it should store your Address data in geolocation fields as well.