If Menu custom rule for MemberPress

memberpress-if-menu-custom-rule.php

<?php
function mepr_custom_rule_menu_condition( $conditions ) {
	$conditions[] = array(
		'id'        =>  'memberpress-rule-50',                              // unique ID for the rule
		'name'      =>  __( 'Memberpress access rule 50', 'i18n-domain' ),  // name of the rule
		'condition' =>  function( $item ) {                                 // callback - must return Boolean
			return current_user_can( 'mepr-active','membership: 50' );  // paste MemberPress condition here and returns it
		}
	);

	return $conditions;
}
add_filter( 'if_menu_conditions', 'mepr_custom_rule_menu_condition' );