How to get subscription id programmatically in a Azure Role?
Sorry Gatis, there is no way to get this via any method provided by Azure*. You would need to pass this information into your role using something like the CSCFG configuration settings.
For a little more context - the subscription ID is only known at the RDFE layer. Once you are in the Fabric layer (ie. your running Worker Role) then there is no concept of a subscription ID. You can see http://blogs.msdn.com/b/kwill/archive/2011/05/05/windows-azure-role-architecture.aspx, process A and steps 1&2, for a little more info.
*If you are using AAD authentication for your Service Management API calls then you could get a list of all subscriptions for that AAD user using 'List Azure Subscriptions' - http://msdn.microsoft.com/en-us/library/azure/dn775050.aspx. With those subscriptions you could enumerate all cloud services and match the deployment ID to the deployment ID for your worker role.
Edit: Typo in first paragraph. Changed 'something like the Subscription ID' to 'something like the CSCFG configuration settings'.