After a fresh installation, users will be given a 28 day trial licence. After the trial period SQL Data Catalog will become read-only - editing classification data or taxonomy will be disabled. Functionality is restored when a valid serial number is entered.

Activating a trial licence happens after the product is installed.

After an installation, the Configuration App runs and this now offers you a button, "Manage license..." to go to the licence management dialog.

If you press the button you will be prompted to log in with your Redgate ID:

If you don't have a Redgate ID, you can get one using the "Don't have a Redgate ID?" link.

After logging in with the Redgate Id, you will be offered a 28 day trial of the product.

You can get back to the licence management by running the configuration application %PROGRAMFILES%\Red Gate\SQL Data Catalog\ConfigurationApp\RedGate.SqlDataCatalog.ConfigurationApp.exe

This requires Administrator permissions, so may elevate when you run it. Use the "Manage licences" button to start the trial as above, and then close the configuration application without pressing "Finish".

There is a License section on the Settings tab where you can see the license state, and also activate and deactivate licenses.

For additional information, you can check Managing your Redgate ID.

For troubleshooting, you can check Unable to connect to the Redgate Client Service.