At any time it is possible to move from your on-premises installation to a Cloud instance and vice versa.
No credits will be recognized if you change from on-premises to cloud nor if you change from cloud to on-premises.
If you move from on-premises to cloud, you will be required to purchase a new Cloud system from scratch. The actual license will continue to stay active and you can continue to use the local installation as before.
If you move from cloud to on-premises, you will be required to purchase a new license from scratch. The actual cloud installation will continue to stay active and accessible until the end of your contract.
A paid migration service is available for migrating your actual data to the new system.
This document is published at the "Move from On-Premises installation to Cloud and vice versa" section of this site and is subject to updating.