Transfer, no, since UKARA is a way for a specific site to verify that they know your face. When a site closes, UKARA should wipe those registrations.
However, the Mall is part of Zed Adventures, who have their own ZED UKARA code, and they're still running Battle Lakes in Kent. So I doubt that UKARA could just wipe all those ZED registrations even if they were minded to.
I reckon you'll be good to continue with your current ZED code until it expires. I mean, that's if retailers even bother to verify the code in the first place.