Enscape frequently pings its activation server. If a key is flagged as being used on too many machines, it is instantly blacklisted.
Ensure you are on the latest sub-build of 3.0 (e.g., 3.0.2). Bug fixes often resolve licensing "handshake" errors. enscape 330 license key work
Once you have purchased a license or signed up for a trial, follow these steps to ensure the software works correctly: Enscape frequently pings its activation server