Problem:

I kept seeing a warning that Toolset plugins couldn’t connect to toolset.com due to a site key mismatch, even though the plugins worked fine.

Solution:

Unregistered and re-registered Toolset from WordPress Dashboard → Plugins → Add New → Commercial tab → Unregister Toolset → Register Toolset → Get a key for this site → paste the new key and confirm. The warning message disappeared afterward.

Relevant Documentation:

https://toolset.com/faq/how-to-install-and-register-toolset/