Here’s a thought. Let’s say you find an app in the Windows Store that you like, but isn’t free. Take “Hydro Thunder Hurricane” as an example – it’s a really fun 3D game. Now, let’s say you decide to buy it. You may have a couple of questions:
The answer to all of these questions is “no”. That is, you only need to buy it once and you can use it on multiple devices, and across multiple accounts.
With this approach you can make sure that you only pay once for the Windows 8 apps that you buy, whether it’s on a different machine or on a different account.
PS to change accounts on Windows 8 (or Windows RT), get back to the Start screen and click or tap on the user name & picture at the top right. You’ll see a list of users, just select the one you want to log in.
If you open the store app and goto Your Account. It states that you can install app on 15 PCs, not 5.
Interesting, when I do that it definitely says 5 PCs, not 15. I have tried it on a few machines. I'll see if I can get to the bottom of it, thanks for flagging
Update: With Windows 8.1 release you can now install it on 81 devices. Result!