Multiple Apllication on same account

​@santosh You are able to promote more than one integration key into production. 
A single Docusign production account can handle multiple integration keys. 
If you already have an integration key in production (key A), you can promote another integration key (key B) into production and it will have no impact on key A. 
The integration keys are separate from one another. A common example might be if you’re using Docusign with a 3rd party tool and this is what key A is used for. 

Months later you might develop your own custom C# code for a data export system using key B. The two keys (A & B) have their own unique tasks and work independently from one another. 

Expanding on this example further, lets say you also need a 3rd integration key (key C) for auto deleting users once they leave your company. You might task an employee to do this and they choose to build a Python application for this task. This could be handled by key C. 

Technically you could use one integration key for all integrations in the example above but having multiple integration keys can make more sense if you’re wanting to have logs independent for each individual integration key and for possible organizational purposes.  

In other words, promoting more than one integration key to production is normal and totally fine to do. It’s also ok to have just one integration key for all your integrations.
It’s ultimately a business decision based on your use case and if you do want more keys promoted to production you’ll need to run through the steps shown below to promote as many integration keys as you need in production. 
https://developers.docusign.com/platform/build-integration/

https://developers.docusign.com/platform/go-live/