Hello Kevin,
Thanks for reaching out to us! Let me help you out with that question.
If you simply want to get rid of that invalid message, then you can remove the license keys from Events > Settings > Licenses. You will still have full functionality of the plugin, you will not get automatic update for that site though.
If you would like to change the site where your license keys are, then here is an article that should give you the information on how to do that:
Moving your license keys
And this article might be helpful as well:
Using One License for Live and Dev Sites
Let me know if this helps.
Cheers,
Andras