wc_get_product_id_by_sku

wc_get_product_id_by_sku from Pastebin

    
        event_rsvp ) {
		// update event product
		$sku = 'EM-' . $EM_Event->event_id;
		$product_id = wc_get_product_id_by_sku($sku);
		if( !empty($product_id) ) {
			wp_set_object_terms( $product_id, 'custom tag goes here', 'product_tag' );
		}
	}
	return $result;
}
add_filter('em_event_save', 'em_woocommerce_default_category', 99999, 2);