The message tells you which case you are in:
- “Please connect to the internet”: the add-in could not reach the license server. It keeps working for 7 days after the last successful check; reconnect once and it re-verifies by itself.
- “This license key is not valid here”: usually a typo, or a key from one of our other products. Each add-in has its own key; copy it straight from the purchase email.
- “Active on its maximum number of devices”: free up an old device in the device manager, then try again.
