Thanks, Geoff.
Got it. The problem is, though, that I cannot update from WordPress because I am getting the message:
>There is new version of Event Tickets Plus available but your license key is out of installs. Visit the Events Calendar website to manage your installs, upgrade your license, or purchase a new one.
As I’ve said, I have already removed the license key from the old site. According to the link you sent, the next step is to “Disconnect” the License Key from the Original Site … herein lies my problem. This license key is not in my account. Someone else originally built the old site and purchase the license on behalf of the customer. The new site is for the same customer, and we did not change anything about how events/tickets work. The functionality was essentially cloned over. Thus, we are attempting to use the same key on the same domain, at a different host. But for some reason, it’s not being recognized that there is only one site with this license key.