Lots of companies have an Azure Enterprise Agreement (EA) where they buy large chunks of Azure-dollars, and in return get some kind of discount. I won’t go into details about EA, but here’s a quick introduction:
EA will let you create multiple subscriptions connected to your EA account. All usage on these subscriptions, will be billed from the EA account. You can also create departments where subscriptions can be assigned, and even have account owners who manage the subscriptions in their specific department.
Another Microsoft offering that a lot of companies have, is MSDN subscriptions. This let’s them test software like SQL Server, Windows, Windows Server, System Center, an so on. In Azure we don’t have Windows client OS available, because licensing prevents it, unless we create a subscription connected to our MSDN subscription.
So far so good. Now imagine having both EA and MSDN, and get the best from both worlds. Luckily Microsoft let’s us use MSDN offerings on EA, let’s take a look at how this is configured:
First, log on to the EA portal: http://ea.azure.com. Next, select Manage on the left, and then Account in the top:
Next, find the account you want to enable MSDN for, and choose Edit on the right. After that, check the box next to MSDN and click Save:
That’s it, now MSDN is enabled on subscriptions under that account. So easy!
…no, of course it’s not that easy 
There is no way to enable MSDN on existing subscriptions. You will have to recreate these as MSDN enabled subscriptions. Yeah, annoying, I agree. Anyways, to create a MSDN enabled subscription, sign in as the account owner, and browse to Manage –> Subscription –> +Add Subscription:
In the popup window, select Microsoft Azure Enterprise MSDN:
And that’s it! Really, not kidding this time 
Cloudpuzzles 