How to move your Mac App bought from the Mac App Store

there are several ways.
you can either just copy them to a USB device, then copy them from there to your new mac.
or your simply log into the mac app store on your new mac with your apple ID and re-download them, you won't be charged again.

From the Apple Article
http://support.apple.com/kb/HT4482

Summary
The Mac App Store remembers all apps you purchase with your account. Apps you purchase and install from Mac App Store can also be copied to an external hard drive, USB Flash Drive, CD/DVD, or backed up via Time Machine.


If you purchase an app and then delete it, you can use Mac App Store to reinstall the app (if it's still available) without incurring additional charges to your account.

1. Open Mac App Store (it is called App Store on your Dock or in the Applications folder).
2. Select the Purchases view at the top of the window. App Store will show all apps purchased on your >account.
3. Click the Install button next to any available app displayed to reinstall it on your Mac.

If you save a copy of an app to removable media (such as an external hard drive) or file share, simply drag the app back from its storage location to your Applications folder. When you open the restored app for the first time, you may be required to sign in with the Apple ID account that was used to purchase the app.