when i click install GSX pro from my email (when i purchased it) it sas link expired, how can i get GSX pro reinstalled back on my pc.
That's because you read the email from Digital River, which has links expiring after 30 days.
If you read the email from FSDT (we send a separate email with your key precisely for the reason you won't be confused by Digital River download expiration ), it would have told you that, while downloads on Digital River expire, it's not a problem for our products, since they are all installed through the FSDT Universal Installer, which is always freely available here, and it only needs your key to redownload.