When you list your car, the pricing page will include the option to limit availability only to members of your club(s). There are multiple options, so you can select the club(s) to which you want your car to be available.
If you already have a car listed, you can change its availability in the “My Cars” tab. Choose your car then visit the “Availability” tab (the first tab). You’ll see an option on the top of that page titled “Car Available To” and you can choose “Everyone” or limit your car to your club(s).
This selection is made per car, so if you have multiple vehicles listed on DriveShare you can choose whether or not you’d like to limit availability for each individual car.
Additionally, when you view your own vehicle listed on DriveShare you’ll see the notation “Available to members of Porsche Club of America” below the fee summary section.