Loyalty system

I admire loyal customers. You earn loyalty points for each purchase, which you can use in the next order for additional discount.
1 point = 0,04 € discount for next order. For each 1 € of purchase you earn 1 loyalty points - circa 4% value of order.
Loyalty points have limited validity - 180 days.
Loyalty points can be used in shopping cart - left down corner button: "use loyalty points".
Maximum discount is 20%.
Loyalty points can be used by only registered customers