First, open the License tab of AI Engine: it tells you the actual problem (the license server can’t be reached, the license is not activated on this site, or it has expired), and you can copy the diagnosis to send it to us. You can also remove the AI Engine license, save, re-insert the license, save, and try again.

This might be because your URL changed, even slightly. Make sure on your meowapps account that the domain linked to the license matches exactly with the website where you intend to use it.