I've just added a new module: juce_tracktion_marketplace!
It contains some classes that make it easy for an app/plugin to communicate with a web-store and find out whether the product is registered on that user's machine. It also has some GUI for allowing a user to enter their name/password, and for handshaking with the web-store to complete the registration process.
As the name implies, the module was written to provide support for our new "Tracktion Marketplace" - a web-store for selling 3rd-party plugins. The module will provide code that'll make it a no-brainer to add support for selling a plugin on the Tracktion store. But the module itself isn't tied to the tracktion website, and provides both client and server-side functionality, so you could use it to implement your own web-store if you want to go through that painful process yourself!
Class API info about the key classes is here:
http://www.juce.com/api/classTracktionMarketplaceStatus.html
http://www.juce.com/api/classTracktionMarketplaceUnlockForm.html
More about Tracktion Marketplace coming soon.. It's currently in beta, but if you're interested in selling products on it, get in touch!