The plugin itself does not store anything locally.
However, at the discretion of the application developer and the plugin user, it is possible for the Plugin user to store some data. For example, during a call, you can record your own screen. Or the application developer could use the getFrame() feature to capture individual frames.
This is the same as when you use Google Chrome, Mozilla Firefox, or a video conferencing application.
Temasys does not have any way of checking, or capturing the data that flows through the plugin.