How does one go back to DT Pro Office? This forum suggests it is possible. It tried to install DT Pro Office and my valid license info does not work. I had never entered an organization and as such left that field blank. So … can’t even install DTP Pro Office much less start on the downgrade process. I would very much like to return to that version I muccccccch prefer. If … IF I work out the license issue … will DTP Pro Office open current DB’s? Is there a standalone utility to convert them if required? How is it done?
If you purchased DEVONthink 3 Pro or Server, the license can by used to license DEVONthink Pro Office.
However, despite your preferences, you should not plan on using the 2.x line for an extended period of time. It is no longer under development. Also, if you persist in this, you should never upgrade beyond macOS 10.14 Mojave.
And no, there is no conversion utility as the file format has not changed.
The more interesting question obviously is: why would you want to downgrade to a version that is no longer being developed and limits you to upgrade your OS?