Show posts by author of membership level (Paid Membership Pro)

$ids = get_users( array('role' => 'author' ,'fields' => 'ID') );
$contr_limit    = count($ids);
for($cntr=0; $cntr < $contr_limit; $cntr++){
       if( pmpro_hasMembershipLevel($level_id, $ids[$cntr] ) !== true ){
            unset($ids[$cntr]);
       }
}

$args = array(
        'author' => implode(',', $ids),
        'orderby' => 'date',
        'order' => 'ASC',
        );