On your website, Google maps are displayed thanks to the Google API Key.
This key is linked to your Google account and will allow 25000 views/month for free.
In the past, once this limit was reached, the maps would have stopped working on your website unless you had a paying option on your Google account.
Please note these conditions have changed on July 16, 2018, Google has updated its conditions and you'll be requested to enter your credit card information in your Google account in order to get a Google API key.
You will not get charged by Google unless you go over the amount of 25000 views/month.
You'll find more information about the changes to your Google Account here.
If your account is impacted and if you want to keep using the google map feature, it's important that you can follow the Google migration process here.
Once you have your Google API Key, you need to enter it in Website Builder app> Preferences>Integrations.