Yesware is licensed by email address and not by computer or download.
If you are using the same email addresses across different computers, you would need to download the application on that new PC or Mac computer Here and then authenticate using your inbox's log-in credentials.
If you are using different email addresses, each will need their own license. You can add additional licenses to an existing account HERE.
Please Note: Any newly added email addresses will need to have their own log-ins and passwords. Yesware does not work with Alias or 'Send As' addresses.