Under the developer account it is possible to list service subscriptions, but:

• the state is not shown (Pending/Approved)
• it is not possible to change state from this view, and it would be useful.

The thing is that when a developer subscribes to a service plan that has approval enabled, the provider receives a notification:

You can approve / reject the application from your 3scale Admin Portal.

And the link leads to the account page. But there is no action that can be done there :/