When you bought Pro, you would have recieved a link to your Pro personal download page (for updating your Pro during the 6 month period). You should've bookmarked or saved this link somehow. You can simply use this link to download a new version of Pro at any time. But if you're using an older version (the current version is 4.12.6) & want to continue using that same version... you'll have to save a copy of the installer for that version.
There's nowhere for you to download an installer for an older version of LW. Saving installers is up to you