You can download an app you purchased before on the Mac App Store by following these steps:

  1. Open the Mac App Store on your Mac.
  2. Click on the “Purchased” tab at the top of the window.
  3. Find the app you want to download and click the “Install” button next to it.
  4. If prompted, enter your Apple ID and password to start the download.

If you don’t see the app you’re looking for, make sure you’re signed in with the same Apple ID you used to purchase the app. If you still can’t find it, contact Apple Support for assistance.