Writing Shed for IOS v5.00 has just been released on the AppStore and should be with you sometime over the next few days.
The primary purpose of V5.00, apart from a few minor fixes, is the introduction of a new payment model. Ever since the first release four years ago the app has used the single payment model. You pay once and get all the features forever. This approach is no longer financially viable, so all new users will use a subscription model. This means that use of the app requires a regular monthly or yearly payment. Users get the first week free to try out the app and can cancel at any time using the Settings app on their device.
Existing users, that is those using pre v5 versions will be unaffected by this change and will continue to enjoy uninterrupted use of the app. They will also continue to receive software updates. They will never be asked to subscribe to the app.