Questions about Discount Coupons

Hello, I would like to ask if the coupons that were given at the end of the year 2019 are still available for use on this date? And if the coupon has any duration such as daily, weekly or monthly? Or is it for single use only for one item? I would also like to ask how the conversion works for the calculation of payment in coins .. for example: if I want to buy an item that costs 9 coins if I use a 40% discount coupon [9 * 0.6 = 5.4] I would have to pay 5 or 6 coins?

5.4 = it will cost 5.
if 5.5= it would cost 6 I guess but you can see the new price once you insert the Code before to complete the process. So, do not worry

It does NOT expire.

thanks mate for the info