function my_edd_grandfather_renewal_discount( $renewal_discount, $license_id ) {
	if ( ! $license_id ) {
		return $renewal_discount;
	}
	$license = edd_software_licensing()->get_license( $license_id );
	if ( ! is_object( $license ) ) {
		return $renewal_discount;
	}
	if( ! empty( $license->date_created ) && strtotime( $license->date_created ) < strtotime( 'April 1, 2018' ) ) {
		if ( $license->is_expired() ) {
			$renewal_discount = 20;
		} else {
			$renewal_discount = 30;
		}
	}
	return $renewal_discount;
}
add_filter( 'edd_sl_renewal_discount_percentage', 'my_edd_grandfather_renewal_discount', 10, 2 );