Once you are logged in via the SlideME (SAM) app with your limited account, you can either convert by visiting MyAccount; or when you attempt to download any application you have yet to install onto your device, the full registration form will appear for you to complete.

Make sure you alter the system generated username from "fastreg_..." to something else of your choice. It is for this exact reason the field is editable from within SAM 5 and up. You can only make this change from SAM and only once since the change from Quick registration to Normal (full) account is a one-time conversion.