To upgrade from an earlier version of Merge:
Ensure that your serial number’s support expiry date is after the release date of the version of Merge that you are installing. For more information about serial numbers and support expiry dates, please see Understanding Serial Numbers, Support Expiry & Upgrade/Support Entitlement.
You do not need to uninstall an older version when upgrading, but please ensure that you update all the different components of Merge (main application, Finder integration, path to the command-line utilities). Merge is unlikely to function correctly if there is a mismatch between installed components. For more information, see How to Install.