There is no such option for individual tabs in a tab control. Keep in mind that Form access really only defines whether a user can see the particular form in the top level menu. There is nothing that prohibits the user from seeing the form when it is opened by for example a microflow. As a result of the way this works, defining security on individual tabs would currently not be possible. In our upcoming 2.5 release this feature has been renamed to Form Visibility.
Edit: As Fedor already said, this feature is now being enhanced in 2.5 and will include more options for showing tabs.
Hi Kees, you're totally right about the logical security extension of tab control in a form. Our developers are going to make this available in our upcoming 2.5 release!