The Quality status on some of my Tags are showing as Demo Expired although we have a licence, what could the reason be for this?
Has the system been reset at all since applying the license?
One possible way that this can happen is that all your tags go to trial expired because the demo time runs out, then when you reset trial or apply a license the client does a huge read of all your tags to try and clear all the trial expired qualities and some parts of that read time out. This can leave a couple tags with trial expired quality until the next time the value for that tag is read or the value changes.
You might just try restarting the service, restarting the UA module (assuming these tags are all coming from the UA server), or even just forcing the OPC connection to reconnect by doing an edit/save on it without changing any settings.