It is not possible to change
Used by subscriptions parameter for a domain in Unregistered status:
The settings have been saved successfully is displayed, but actually
Used by subscriptions remains unchanged.
Such behavior was classified as software issue PBAS-30603 and will be fixed in future OBAS releases.
Please consider watching Odin public sources for information about updates in our products:
Knowledge base, each product update comes with a corresponding KB article.
Since the hotfix requires complex manipulations with the database, it is recommended to contact Odin Technical Support for assistance.