I've contacted support three times now with no response. Upgraded my license in Sept. and when trying to register by double clicking the key I get a message that states my license is no longer valid for this version. Checked to make sure it is the correct key and not the old one and it is. Anyone run into this?

you could be running a wrong product (Ultimate vs XTreme) for example?

and if you contacted support via email reason you didnt get a reply is bc winstep is one-man-operation, and the developer has been away for a while

I'm afraid as seeker pointed out, the developer is currently temporarily absent. For the current state of affairs, see the most recent service announcement in the 'Announcements' forum.

As for your registration problem, along with your licence key you would have received a text file giving detailed instructions how to activate the registration. Follow this to the letter and everything *should* be fine.