<?php
    
    $the_post_object = get_post( $post_id );
    
    $access_list = MeprRule::get_access_list( $the_post_object );
    $product_ids = (isset($access_list['membership']) && !empty($access_list['membership'])) ? $access_list['membership'] : array();

/*
    $acces_list returns: ["membership" => [1,2], "member" =>["foo"]]
    $products_ids contains an array of Membership IDs that can access this content
*/