However, as Windows evolves and Nitro shuts down legacy servers, you may find the activation process increasingly difficult. If the online activation fails, try the registry hack for the activation server. If that fails, you are likely facing compatibility issues with modern TLS encryption.
Use trusted key finder tools (like Magical Jelly Bean KeyFinder or ProduKey) to scan your old installation. Nitro Pro 9 Activation
If you bought directly from Nitro, go to the Nitro PDF Pro login portal. However, since Version 9 is legacy, your account may have been migrated. Try the "Resend License" option. However, as Windows evolves and Nitro shuts down