federated-wordpress-customizations/shared/federated_woocommerce_shared_functions.php

<?php

if( ! defined( 'ABSPATH' ) ){
    exit; // Exit if accessed directly.
}

function get_subscription_tier($subscription){
	$tier = '';
		foreach ( $subscription->get_items() as $line_item ) {
			$product_id = $line_item['product_id'];
			$is_core_product = get_field('subscription_type', $product_id) === 'core';
			
			if($is_core_product){
				$tier = get_field('subscription_tier', $product_id);
			}
		}
	return $tier;
}