How to Re-Download Purchased Apps

Once an app purchased from App Store has been installed, the buy button of the app on both the product page and Purchases page become grey and turn into  [ INSTALLED ]

In theory, unless you remove the app from your machine, you won’t be able to re-download the app. However, the steps below will allow you to download an installed app again without prior to removing it from your computer:

1) Log in to App Store with your Apple ID

2) Go to the Purchases page

3) Press and hold the  [ option ]  key while clicking the app your want to re-download

4) You will be taken to the product page where the buy button changes to  [ INSTALL ]

Now you can re-download the app.