18
Most MSDN subscriptions are a perpetual license. When the subscritions expire, you still have the legal right to use everything that was included in it. However, this might not be the case for some volume license subscriptions, so you'll want to check out your specific subscrition to be sure. I've had expired volume license subscriptions in the past that have locked me out of viewing the keys - so you'd want to make sure you download all the keys before the expiration date.
Quote from MSDN FAQ - "In most cases, MSDN Subscriptions come with “perpetual” use rights—the ability to continue using the software after the subscription has expired."
See here for more info... http://msdn.microsoft.com/en-us/subscriptions/cc150618.aspx