As already stated, you just need to log into the store with the account that purchased the app under the user that you want to see it.
From:
Licensing apps - Windows Store for developers - Site Home - MSDN Blogs
Apps can be installed on multiple PCs and user accounts
These days, people may use several PCs in the course of their daily lives, or share PCs with more than one person in their household. We want these customers to have access to a great Windows 8 experience on all of those PCs.
The licensing terms allow customers to install and use their apps on any user accounts on up to 5 PCs. Why only 5 PCs? Because we also believe in the value of the developer’s investments in their apps, and we want to protect that investment from abuse.
You can view your list of apps by selecting View your apps on the Account and settings page. Jonathan Wang’s post, Designing the Windows Store user experience, describes this page in the Reacquiring apps section. This image from his post shows the customer selecting 4 apps to install from their list:
Your apps page with 4 apps selected, and buttons to install, view, select all, or clear selection.
See all of your apps and reinstall them
From this page, you can install your apps on a different user account on the same shared PC.
Say, for example, that your family has a shared PC. You have previously used your Microsoft account to purchase a game that all your kids like to play. You can install it for each of your kids by having each of them sign in to their Windows accounts on the shared PC, then launch the Store and sign in to the Store using your own Microsoft account. There, you’ll see all your apps and you can re-install the app on your kid’s Windows account. Installing apps on multiple user accounts on a shared PC still only counts as one of the five allowable PCs where you can install apps.
Note: The Windows 8 Customer Preview release does not yet fully support signing in to the Store with a different account if a Microsoft account is connected to the Windows account.