Know When Your Windows Live Hotmail Account Expires

After 270 days (about 8 and a half months) without access, a Windows Live Hotmail account becomes inactive. This means all messages stored in the account are deleted and no new mail is accepted.

When Your Windows Live Hotmail Will be Deleted and Reassigned

People who try to send email to an inactive Windows Live Hotmail account get their message bounced back with a delivery failure. You can still use your account name and password to log into Windows Live, however.
After 360 days (five days short of a typical year) of inactivity, a Windows Live Hotmail account is permanently deleted. If you don't use your Windows Live ID (which is your Windows Live Hotmail email address) for 365 days (about a year), it, too, can be permanently deleted. Somebody else can take your Windows Live Hotmail address!

Does POP3 or Forwarding Count as Accessing a Windows Live Hotmail Account?

If you access your Windows Live Hotmail account in an email program or service via POP or have Windows Live Hotmail forward your mail, this is not the same as accessing your account via the web.
To keep your Windows Live Hotmail account active, you have to log in via the web every 8 months, at least. Mark it on your calendar or to-do list perhaps.

Paid Windows Live Hotmail Account Remain Active Throughout the Subscription

Paid Windows Live Hotmail Plus accounts do remain active for all the subscription time, of course, whether you access the account or not.

Delete Your Windows Live Hotmail Account Yourself