Following a variety of direct mailings from Xara offering different discounts, it seemed to have twigged and has resurrected its original and best offer.

The mechanism is probably easiest if you get a free Xara Cloud account and then pick Upgrade.
Without checking, you should be able to add in the discount coupon LIFETIME to get 50% off.
I assume the same will apply for a renewal if you already have the Xara Cloud+/Xara Designer Pro+ combo.

You can also try this link: https://www.xara.com/shop/proplus-annual/.

I also imagine if you stop the subscription, you will only get an ongoing reduction if the offer is still around.

Did you know that you are eligible for an exclusive 50% LIFETIME discount today and for your future renewals?
Use the coupon to get Xara Designer Pro+ at the best price, with all the latest updates and many more to come.
Acorn