You may lose access to your favorite App that you might have purchased from the Microsoft windows store. The news comes directly from Microsoft and it was stated that Microsoft can kill purchased app unexpectedly which means they can actually discontinue access to any purchased app for various reasons including security, and legality related issues. Their terms of service allow them to do so.
Microsoft windows store will provide a large number of features to the user. On one hand, users will be able to search and purchase apps from the windows store. On the other hand, developers will be able to submit apps developed by them into the windows store after approval from Microsoft.
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On its darker side for users, any app purchased by them from the windows store can be discontinued by Microsoft at any point of time for any reason. It does not matter if the app to be discontinued has been purchased and has been in use by several users. Some apps, which work successfully on one device, may not work if user try to use them on some other device. In such cases, users will be responsible for making backup of their data that are stored in the app in use. If the app is discontinued, Microsoft bears no responsibility for the loss of the user data. From these facts, it is evident that Microsoft can remotely kill purchased apps without giving a reason.