Is it possible to upgrade Plesk Preview version to Final one when it is released?
Plesk Preview build does not have any limitations. However, this is not officially supported way. Plesk Preview version is not intended to be upgraded to Final one. However, in practice, it is possible by using option '--all-versions' for Plesk installer.
As one of the possible scenarios, the migration to the new server with General Release being installed may be done.
Note: An upgrade from Preview version to Final version is not supported scenario by Plesk Support and should be done on your own risk.