I want toolbar no longer functions if a member leaves

[Webmaster]

I would like to create a toolbar for my private members. What can I do to
make sure the toolbar no longer functions if a member terminates their
membership and leaves?

[Admin]

We can suggest you to generate your toolbar configuration file (basis.xml)
on your server using some script (php/perl/asp) and it will be
downloaded by toolbar after some period of time (you can set it - once
a day, for example). When user installs his toolbar , he will be asked for username/password and these values will be stored inside the toolbar. When toolbar opens you script url - script will get username/password from the toolbar and according to it - will generate fully functional toolbar
or some kind of demo-toolbar.