Yes. OutSystems is designed for portability between data centers. Application data, meta data, configuration data and source code are all carried through to the database, making portability much simpler than with other technologies.
At the end of a transition, all applications will continue to run as before, with all the great functionality an organization's users have grown accustomed to.
The transition to on-premises entails the following steps:
Install the platform in the new data center.
Ensure connectivity to all integration points and external data sources.
Migrate the data.