If you are a group member and another member of your group is subscribed to Premium Service, you can enjoy all the benefits of Premium Service. However, Premium Service features will be limited to the specific group only.
In order to use Premium Service features, make sure that the group is selected in the group selector. The group selector can be found at the top of the friends list. It may be defaulted to "All Friends" until you select the specific group.
Once you're in the group, you will be able to view the group members' location, location history, and Driving Report. You can also receive Alerts from the group members.