Go to
https://www.citibikenyc.com/helloTry Citi Bike free for 14 days (with no obligation) and experience for yourself a better way to explore your community. Your trial includes unlimited 45 minute rides on any of our 7000+ bikes located throughout Manhattan, Brooklyn, Queens and now Jersey City. At the end of the 14 day trial period your membership will convert into a annual plan unless you turn off auto-renewal in your account settings. Citi Bike costs just $149/year (plus tax).
I Think the way they limit is by cc, so as long as this lasts, free citi bike ;-)
(I was told it's expiring today but didn't see that anywhere)
You can log onto your account, and stop auto renew