OnStar is a subscription-based service that offers a variety of features to its users. While some of OnStar's services can be used without a subscription, most of the features require an active subscription in order to work.
Without a subscription, OnStar users can still access emergency services and roadside assistance by pushing the blue button on their OnStar device. They can also use the OnStar app to locate their vehicle if it is lost or stolen. However, other features such as hands-free calling, remote door unlock, and turn-by-turn navigation will not work without an active subscription.
Overall, while some of OnStar's features can be used without a subscription, the majority of the features require an active subscription in order to work properly.