Also hide members-only "products" CPT from archives.

my_hide_members_only_products_from_archives.php

<?php
/**
 * Also hide members-only "products" CPT from archives.
 * You must use the PMPro CPT Add On and then check a produc to require membership.
 * And also set the "Filter searches and archives?" option to Yes in the PMPro advanced settings.
 */
function my_hide_members_only_products_from_archives( $post_types ) {
	if ( ! in_array( 'product', $post_types ) ) {
		$post_types[] = 'product';
	}
	
	return $post_types;
}
add_filter( 'pmpro_search_filter_post_types', 'my_hide_members_only_products_from_archives' );