Upgrading to the verified track will give you access to all materials, including graded assignments, until the course end date.
Upgrading will extend your access to the course content but it will not change the course end date.
You’ll still need to pass the course before it ends in order to earn a certificate. After the course end date, as a verified learner, you will have access to archived course content and materials, as long it's hosted on edX.org.