Conditionally load script if there is a gallery in a page

Hi!
I’m using Nextcellent Gallery with Flexslider, and I have enqueued the Flexslider script in my theme’s functions.php

Currently the script loads on all pages.
I would like to know how can I load the script only when there is a gallery in a page.

Something like this:

if (page_has_gallery()) {
	wp_enqueue_script( 'flexslider', get_template_directory_uri() . '/js/jquery.flexslider-min.js', array('jquery'), '1.0.0', true );
	}

Is it possible?
Thank you!

https://www.ads-software.com/plugins/nextcellent-gallery-nextgen-legacy/