Thank you, Casey.
I suppose the root of the problem is that I have a message from Tribe in my WordPress install, admin side, telling me:
Sorry, this key is out of installs.
My key does not expire until Nov 2014 and I am not sure where else it would be installed.
One guess is that the URL currently associated with they key was my development folder; the site has subsequently moved to another folder on the server. The folders are mapped but perhaps I should disconnect the key from the dev domain and update it with the live URL? Will I experience any data loss if I take this step?