In the phone dev centre there was a nice link prompting me to renew. On that renewal page there was an option to pay for renewal or enter a code. Obviously I wanted the "enter a code" option but where to get that code from? Unfortunately it wasn't as easy to find as I would have liked so I thought I'd share it here.
It's actually quite simple (once you know how)
- Log into your account on msdn.microsoft.com.
- Got to https://msdn.microsoft.com/en-us/subscriptions/manage/
- Under the Subsccription Benefits find "Windows Phone developer account"
- Click on the "get code" link to reveal your code - it is a GUID
- Enter that code (GUID) in to the phone dev center renewal page.
Hope this helps.