Reserving an app name
You can reserve an app name before submitting the app (or even building it). Once you reserve a name, you have one year to submit the app to the Windows Store. If you do not submit within one year, you will lose the reserved name and it will be made available should another developer choose to use it.
Note Make sure that you have the rights to use the name that you reserve. If someone else has trademarked the name, they can report an infringement and you won't be able to keep using that name.
Go to your Windows Store Dashboard. (You can do this by clicking the "Dashboard" link found near the top of any page in the Windows Store apps Developer Center.)
Click Submit an app.
Click App name.
In the App name text box, enter the name that you want to use.
Note Be sure to enter the name exactly as you want it to appear. Double-check your spelling, capitalization, etc.
Click Reserve app name.
Note If this name you entered is already reserved or in use by another developer, you'll see an error message and won't be able to reserve that name.
Make sure that you use the reserved app name as the DisplayName in your app's manifest.
Note This value must be no more than 256 characters.
If you are unable to reserve a name for which you hold the trademark or other legal right, or see another app in the Windows Store using that name, contact Microsoft.
If you want to reserve additional names for your app for use with other language versions, see Entering your app's name.