Unsubscribing from a Subscription plan

We are offering two subscription plans:
Free ($0.00) annual plan that renews automatically. This plan is upgradable to the Paid plan.
The Paid subscription plan renews every month.
Please note my questions below:
Users can unsubscribe from Free plan -  it works fine.
What if the user has already upgraded to the Paid plan? How should the workflow be handled? 
Please advise.

The paid plan can be unsubscribed from same as the free plan. Meaning they can completely cancel the subscription. If it has recurring payments they can optionally cancel just the recurring payments and keep the remaining time on their subscription, which based off your description will expire when the month is up.