How do I upgrade to a couple account?

To upgrade to a couple account, login to your profile and go to the "Upgrade to a couple account" link. When you upgrade to a couple account, your account still ends 1 year from the date of your current subscription's payment (not from when you upgrade.)

Remember, you should only get a couple profile if you will always be travelling together, you should not apply to hosts for just one person from a couple profile.