Application Domain for PDF Viewer on AEM

[kategamo]

Hi,

I am trying to create a credential for PDF Embed API.

Could you please tell me the benefit of getting a separate credential for sub-domains and the reason why it is recommended to get a separate credential even tho one credential is restricted to the domain, plus any subdomains? 

[Joel_Geraci]

I'm going to guess it's to future proof the applications.