(Updated February 3, 2015)
We provide a free access level for anyone interested in using Canopy. We call that access level, or subscription, Canopy Express.
Canopy Express allows users to download the Canopy application's standard installer, which includes approximately 50+ packages pre-bundled into the installer. It also grants access to another 100+ downloadable packages via Canopy's Package Manager. While it doesn't require a paid subscription, users will still need to register an Enthought account for installing/updating packages with the Package Manager.
The important thing to remember is that if you were previously using Canopy with an Express license and then purchase a subscription, or sign up for a free academic subscription, you do not need to re-download the Canopy installer. The new features of your subscription (additional packages in the repo, Canopy's debugger, etc.) will be unlocked once you restart Canopy and log in with your usual account credentials. One of the key benefits of keeping your existing installation is that you will still have your previous Python environment, and all its installed packages, without needing to reinstall everything.
In summary, the underlying Canopy application is the same whether you downloaded it as an Express user or a paid/academic user, and you can unlock new features by upgrading to a paid/academic subscription via our online store.