Updates are always incorporated into the latest Stutter Edit installer, so to update to the latest version, just download and install Stutter Edit. It is not necessary to uninstall before installing, and it will not be necessary to reauthorize.
Installing Stutter Edit updates will return factory presets to their original state. If you have saved over any of the factory presets with your own settings without changing their names, we recommend you rename those presets with unique names before installing updates (unless you want the original settings back). Installing updates will not affect any presets that you have given new unique names to or created from scratch. Any settings saved with host sessions will also be preserved.
In addition, you can simply back up your presets folder before installing the update if you are unsure if this will affect you. For more information on backing up Stutter Edit presets, refer to this knowledgebase article.