We do not store credit card information nor use auto-renewing subscriptions.  You can renew your subscription at any time even while in a current subscription and it will extend based off of your existing expiration date.  When the subscription expires your data remains on your device and in the cloud.  The app will allow some screens to be viewed while expired but most will forward you into the My Account area to renew to view the desired screen.  You can also renew at any time from http://nc-software.com/apdl where additional subscription terms and discounts may be available.