You can renew support on an existing license of Cerberus FTP Server by requesting a renewal quote here:
Our team will generate a quote and send you confirmation (including a link to view and download).
Each quote has a green "ACCEPT" button that you can use to approve the quote. After we receive approval, we will generate and send you an invoice with secure payment options.
IMPORTANT: make sure you indicate that you are looking for a renewal quote (see screen shot below).