To help compensate me for development time, some plugins will not be free. This will not change how the application works, but in order to use these paid plugins, you will have to purchase a license to do so.
The way you can purchase these plugins is by going to the android market and purchasing the application from there. The application will take up minimal space on your device as there isn't much to them. The application will not even appear in your application
drawer, but it must remain on the device in order for the plugin to function.