A quick answer before this gets closed...my recent experience with MSDN is that
- keys that do not require activation continue to work indefinitely
- products that have been activated continue to work indefinitely
- keys that require activation are historically quite variable in behaviour, but now mostly will no longer activate after your subscription has expired.
- you cannot claim new keys once your subscription expires.
MSDN is an amazing resource and very reasonably priced. Best thing is to regard it as a lifetime subscription. Having said that, we usually make sure we claim a few extra keys before we roll over each subscription. Some work, some don't.
Microsoft has been unhelpful in providing information about this, which I find quite understandable.