Is the free trial only for a new paid subscriber?

Context: The Ghost website has more than one paid tier, all of which have free trials. If a subscriber signs up and gets a 60-day free plan, and in the future changes the plan to another plan that also has a 60-day free trial, will they then get the next 60 days free on their subscription?

How does it work?

  1. Is the free trial only for a new paid subscriber, or
  2. Is the free trial also for a paid subscriber who changes plans?