Can application created within Voiceflow be run/moved to an internal server?

Can application created within Voiceflow be run/moved to an internal server?
We are looking to create a voice application for a client, but they have concerns about where the resulting data will sit and worried that using a third-party means they don’t actually own what was created.
This would be for internal use only.

How do I go about handling this, or is their concerns valid/warranted?

Thanks!