It is understood we need get license for publishing and distributing Store Apps. But it is not clear how much it costs. Please clarify the following:

• We have requirement to not to publish our app in store, but to distribute it internally. Sideloading seems to be option. But we are confused what are costs for doing. For sideloading, it is said we need to buy keys. how much it is? Do we have to pay for each device that uses this sideloaded app? Is there any other costs or related software/license requirements with it? this blog says there is per month subscription fee for devices.
• If submitted to windows store, is there a way to hide from public view and allow the app to downloaded for intended users who are using Windows 8.1? Hide this app in the store will not work for us as it cannot be used with Windows 8.1.

• Moved by Rob Caplan [MSFT]Microsoft employee Friday, June 12, 2015 4:51 PM configuring for side-loading is TechNetty

Hi ArjunaCh,

For the first question, it is recommended to make a phone call directly.
Contact us
https://support.microsoft.com/en-hk/contactus

For the second question, we can sideload the LOB (Line of Busines) apps directly without submitting it to the public.
Here is the whole walkthrough for reference:
Try it out: sideload Windows Store apps
https://technet.microsoft.com/en-us/windows/jj874388.aspx

Best r