If you log into your Nissan account -> Manage Vehicle -> Connected Services -> Manage Account -> Manage Subscription
You can see the subscription options and pricing, both for month-to-month as well as an annual rate.
You can also see the subscription options and prices here:

NissanConnect Pricing & Vehicle Compatibility | Nissan USA
Learn about which Nissan vehicles are compatible with NissanConnect as well as NissanConnect pricing.

Finally, Nissan also gave a special offer you had to contact them about within 30 days of taking ownership. The offer gave you another 3 months of Premium connectivity for 50% off. In short, it was an offer to get you to enroll and put your credit card information into the account so that renewing/extending subscriptions is easy.