If you have followed the instructions, when logged in with a local account and you install first app from Windows Store and enter an email address, that email address will now be used for the Store App (Windows Store is just an app as any other app), so further downloads from Store do not ask any email address.
Originally Posted by drugo
When you then run apps you have installed from Store, and if the app in question needs an email, you will get this dialog for each app:
(I changed the language to Italian to get screenshot in your language.)
To be sure I am giving valid advice, I installed Windows 8.1 Update 1 to a virtual machine using a local account. I then went to Store and installed one app and tested this one more time. As I have told earlier, at this point (installing first app from Store when using a local account), it gave me the option to switch to a Microsoft Account or to sign in to each app using a separate email.
I selected separate email and installed the app. After that I installed a few more apps, Store did no longer ask an email because the email I had given when installing the first app was now connected to Store App. Launching the installed apps first time, I always get the dialog as shown in screenshot above.
I can only repeat: If you follow the instructions, launching any newly installed app the app shows a dialog asking if you want to switch to Microsoft Account or select a separate email for each app.