public static function delete_all_old_meta_keys() {
		global $wpdb;

		$query = $wpdb->query( "
			DELETE FROM $wpdb->postmeta
			WHERE meta_key LIKE 'popup_display_%'
			OR meta_key LIKE 'popup_close_%'
			OR meta_key LIKE 'popup_auto_open_%'
			OR meta_key LIKE 'popup_click_open_%'
			OR meta_key LIKE 'popup_targeting_condition_%'
			OR meta_key LIKE 'popup_loading_condition_%'
			OR meta_key = 'popup_admin_debug'
			OR meta_key = 'popup_defaults_set'
			OR meta_key LIKE 'popup_display_%'
			OR meta_key = 'popup_auto_open'
			OR meta_key = 'popup_click_open'
			OR meta_key LIKE 'popup_theme_overlay_%'
			OR meta_key LIKE 'popup_theme_container_%'
			OR meta_key LIKE 'popup_theme_title_%'
			OR meta_key LIKE 'popup_theme_content_%'
			OR meta_key LIKE 'popup_theme_close_%'
			OR meta_key = 'popmake_default_theme'
			OR meta_key = 'popup_theme_defaults_set'
			"
		);

		return $query;
	}