The error code 1521 suggest that the activation key you've entered is invalid. This can happen if the key has been entered incorrectly or if it's no longer valid for the software that you are trying to activate.
Activation Failed
Activation key is invalid.
Error Code:1521
App:....
How to Resolve Error Code 1521?
To resolve this issue, please re-check the activation key you're using and ensure that it's entered correctly, avoid any typos or mistakes in the sequence. If the key is correct, it's possible that it's no longer valid, in which case you'll need to get a new activation key.
If you've purchased a Stellar software product, you can contact our customer support team, and they'll be happy to assist you and provide a valid activation key. Once you get the valid key, enter it in the activation prompt, and the software will activate successfully.
