The app operates on a "donationware" basis. Users can download a basic version for free, but access to premium content—such as certain app stores (e.g., Anzhuang) or specific system tweaks—requires an upgrade to the "Pro" or "Freemium" version.
These sites often ask you to install a "configuration profile." While this adds an icon to your home screen that looks like an app, it is actually just a web clip (a shortcut to a website) that acts as a storefront for more paid "features". Zjailbreak Pro Freemium Code