Apple recently made it possible for adventurous Mac users to install macOS Ventura ahead of the new system’s final release. A developer account is no longer required; any user can participate. You need only enroll in Apple’s beta program.
We generally don’t recommend that our users try beta versions of macOS, unless you have a high threshold for potential headaches (and good data backups). However, if you are sinking your toes into Ventura’s sandy beaches, be aware that the current release versions of Nisus Writer are not compatible. Nisus Writer will likely crash when attempting to load documents on Ventura.
We are working on updates to smooth over any incompatibilities that aren’t resolved by Ventura’s final release. If you need access to a version of Nisus Writer that runs on Ventura please join the Nisus beta team. We’re already privately testing to make sure we’re ready for Ventura’s release one way or another.
UPDATE: Nisus Writer has been updated for macOS Ventura compatibility (pending Apple’s final release).