Backup Metro apps to install Later or on other PC's

I want to backup my current Windows 8 Metro apps so that I can install them to other PC's or Install them later if I format and re-install Windows 8 again.

I want to install these Metro Modern UI apps on a PC that does NOT have internet connectivity, I want an alternative way to install metro apps.

How can I do this?

I asked a similar question on the Windows 8 Developer chat and Jerry Nixon, Microsoft Developer Evangelist, gave me this answer -

There are two ways to install a Windows 8 app - either through the store or through side-loading. Side-loading has native support on Win RT, Win 8 Pro and Enterprise only. Windows 8 Core can be "enabled" by installing Visual Studio. As far as I know, apps from the store can not be copied and side-loaded to another PC. At least I hope not for IP sake.

As per the Windows Store for developers blog, the two options available are:

• Make the app available through the Windows Store, which means the app must adhere to the same certification policies and process required for all apps in the Store
• Build the app internally or sell it directly to the enterprise, which means IT admins must distribute the app directly to end-users within the enterprise, without involving the Store.

Going by these sources, installing a copy of a Windows 8 Metro app that you own, on multiple PCs doesn't appear to be possible.

The official way to reinstall Metro apps is to re-download them from the Store.

If you enter the store and right-click, you'll get the following menu:

If you then click on Your apps, you can see all the apps you have previously purchased or downloaded but which are not installed on the current PC:

This gives you quick access to the app detail pages to start reinstalling.