If you’re using the shortcode, then it will only display on the page/post you add it to.
If you’re using the provided widget variant, or the shortcode within a text widget, then that will be on every page that uses that sidebar or widget area you added it to. BNE Testimonials doesn’t determine this.
Now with that said, If you’re using a widget and only want it to show on certain pages, then you’ll need to use a custom sidebar plugin that allows you to conditionally select which pages the widget area displays on as a whole such as the plugin WooSidebars. You can also use a plugin that conditionally allows you to set individual widgets on certain pages and post types such as one of these.
