The Google My Business API allows users of the AdWords API to create and update locations in GMB. These locations can then be synced to Google Ads and used with location extension ads.
Verification isn't required to use these locations in Ads, but any edits made this way don't appear on Maps or Search unless the locations are verified. To use online-to-offline reporting such as store visits, you must have a verified Google My Business listing tied to location extensions.
To learn more about the policies on the creation of locations, refer to the Google My Business Guidelines for representing your business on Google.
Advertisers who only need locations to run location extension ads don't need to verify their locations in Google My Business.
If you only have one Google My Business account, sync that account to Google Ads. If the Google My Business account contains a large number of locations, you might want to map locations to individual campaigns or ad groups. To learn more, see Filtering location extensions.
If your clients already have Google My Business accounts, or if you want to work with their verified locations, have your client invite you to their existing Google My Business Account as a manager. Use your credentials in conjunction with your client's Google My Business account ID when mapping to Google Ads. To learn more, see Creating the PlacesLocationFeedData object on the feed.
If you're only interested in Google Ads and don't need to verify or manage locations in Maps and Search, create a single, partner-level Google My Business account that contains all of your business locations. Use label filtering to associate Google My Business locations with specific Ads campaigns. While you can use any custom ID, as long as you keep track of it, one option is to use the Google Ads customer ID as a label.
A partner or agency might manage their location extensions through the manual location extensions feed of the AdWords API. If so, they must integrate with the Google My Business API or use the Google My Business UI to manage location extensions.
The Google My Business API allows third parties to create unverified locations and then use the AdWords API to link their Google My Business account and serve location extensions. The use of unverified locations as Google Ads location extensions doesn't affect Ad Rank.
Labels allow you to tag individual Google My Business locations with custom strings. Labels are primarily intended to provide a way for Google Ads users to associate Google My Business locations with specific Ads campaigns.
While you can use any string, as long as you keep track of it, one option is to use the Google Ads customer ID as a label. Once the Google My Business account is synced with Google Ads, you can associate the Google Ads customer ID with the right location in Google My Business.