In order to request production access, Quickbooks has introduced an App assessment that will include questions related to legal, technical, and security aspects of your application and your business. The app assessment should be successfully submitted in order to get access to your production keys.
The app assessment is app-specific so you will need to complete this questionnaire for every app that you intend to get production keys.
Please see here for more information on how to get Quickbooks Online production access since Quickbooks updates its app compliance criteria to ensure an appropriate level of security and quality. App assessment and compliance FAQ can be found here.
More information on integrating Quickbooks Online with Railz can be found here.