What can Ad Events as a new feature in HubSpot Ads tools do?

Save ad spend on targeted contacts that are not converting.

When you create an ad event in HubSpot based on the user lifecycle changing to customer, and if you don't have any conversions from active campaigns which are targeting your contacts tagged "customer" database, then you can save our ad money on them by effectively stopping the showing of ads to them. 

Also, you can let the ad network (like Google) know about the conversions and they will optimise the bid strategy according to the updated conversions.

The event firing will be triggered on the database changes in the last 90 days. The event will be automatically synchronised with the ad networks based on the event creation.