Unfortunately, I could download the entire contents (Full app) not be downloaded (in AppKauf). As damage can help the customer. In Download loop endlessly. Too bad, the content of demo app I liked. Is nice for light exercises in between and also for longer learning. When Rauf and downloading from the device / Kindle in the cloud, the content will be deleted from InAppKauf! The lock icon is deleted, instead, a download-loop without which the files are opened! After re-download / from cloud to device / Kindle the lock icon is back !!! One-time operation / error? Attention! In INAPPKAUF!