The club is a 12 month program. So, your membership ends one year later.
There is no auto-renewal and you will never be billed again. (You can join the optional graduate program if you'd like to continue and get updated materials each year for the life of the club.)
You also get to keep your access to the membership site and Facebook group once your year is up.
If you're not sure when you joined the club, check your dashboard in the membership site. You will see your cohort name (i.e. July 2018.) That is the month you started.