function custom_format_edd( $value, $field_type, $field ) {

    if ( 'date' == $field_type && 'lifetime' == $value ) {
        $value = strtotime( '+100 years' );
    }

    return $value;

}

add_filter( 'wpf_format_field_value', 'custom_format_edd', 3, 3 );