+1... in order to make purchases from Cydia you must first setup the link to your Amazon or Paypal account through "Manage Account" found on the Cydia main page. It's quite simple and just as secure as purchasing things directly from Amazon or eBay.No, it's linked to an Amazon account or Paypal account. It stores what apps/tweaks/whatever you've purchased so if you restore or get a new phone you can still use them.