When you are testing In-App purchasing in your Windows 8 app, you need to use “Windows.ApplicationModel.Store.CurrentAppSimulator” static class instead of “Windows.ApplicationModel.Store.CurrentApp”. This means you’ll end up writing a lot of code like this:

     var licenseInformation =
#if DEBUG
           Windows.ApplicationModel.Store.CurrentAppSimulator.LicenseInformation;
#else
           Windows.ApplicationModel.Store.CurrentApp.LicenseInformation;
#endif
//...
     string receipt = await
#if DEBUG
            Windows.ApplicationModel.Store.CurrentAppSimulator.
#else
            Windows.ApplicationModel.Store.CurrentApp.
#endif
            RequestProductPurchaseAsync(featureName, true)

Yes this gets ugly really quick. Here’s a neat little trick to get around that. Right below your using statements at the top of your file, simply add this alias mapping:

#if DEBUG 
    using Store = Windows.ApplicationModel.Store.CurrentAppSimulator; 
#else 
    using Store = Windows.ApplicationModel.Store.CurrentApp; 
#endif

And in your code you can now simply write:

     var licenseInformation = Store.LicenseInformation; 
     string receipt = await Store.RequestProductPurchaseAsync(featureName, true);