If you own multiple Android devices, you shouldn't have to buy multiple copies of your apps. Fortunately, the Android Market makes it easy to install all of your paid apps on all of your devices without purchasing them again.
Before getting started, please note that these instructions are for devices running the new Android Market (versions 3.0 and higher). While it is possible to install paid apps on multiple devices through the old Android Market, there's one caveat: the Google account used for the purchases must be the primary account associated with the device. In any case, we've included notes that should make the process clear.
Step 1: Make sure the Google account used to purchase your apps is added to your new device. If it isn't, go to your Android Settings, tap "Accounts and sync," then "Add account."
Note: If you are still running the old version of the Android Market (version 2.3), then the desired Google account must be the first account added to your device. This is because the old Market can only access the device's primary account and has no means of switching.
Step 2: Go to the Android Market. Tap Menu, then Accounts. Select the appropriate Google account.
Note: Again, only the new version of the Android Market (3.0 and higher) has this ability.
Step 3: While in the Android Market, tap Menu, then hit My Apps.
Step 4: Scroll down to the bottom of the list, where you should find a section labeled "Not installed." These are all of the applications that have been previously downloaded and/or purchased on your Google Account.
Note: The old Android Market marks each app as either Installed or Purchased. In our case, we are interested in those marked Purchased.
Step 4: Tap any of the paid apps listed to go to the app's Market page. Hit Install.
And it's that simple. You can install your paid apps on as many of your devices as you like, so long as they are connected to the Google account used to purchase the apps.