After you bought Pro, you would have got an email from LW with a link to your Pro personal download page... once you clicked on the link, you would've been been sent to a page where you could download a Pro installer.

The installer itself wasn't sent via email - just the link to your download page. That's because there might be several new versions released during the 6 months, so LW just send you the link to a download page & then you can download whatever updates you choose while your privileges are current.

But hopefully you still have the installer somewhere & can get your Pro going again