Reply To: Get rid of Yoast SEO Premium nagging

Another method which directly removes the action that shows the notice:

add_action('admin_init', function()
{
	global $wp_filter;

	if (!empty($wp_filter['admin_notices']->callbacks[10])) {
		foreach ($wp_filter['admin_notices']->callbacks[10] as $hook_key => $hook) {
			if (is_array($hook['function']) && $hook['function'][0] instanceof \Yoast_Plugin_License_Manager && $hook['function'][1] == 'display_admin_notices') {
				unset($wp_filter['admin_notices']->callbacks[10][$hook_key]);
			}
		}
	}
});