Upgrade or Downgrade
If you switch from or to the Pro plan, which costs $60/month, your new rate will be prorated for the remaining days in your current billing cycle.
Example:
Assume you're on a plan that costs $30/month and you're halfway through the month when you decide to upgrade to the Pro plan. You would be charged an additional $15 for upgrading for the remaining 15 days of this billing cycle.
Canceling Your Plan
When you cancel your Pro plan, it won't renew at the end of your current cycle. You will, however, have full access to Pro features until then.
Example:
If your Pro plan renews on the 1st of each month and you cancel on the 15th, you won't be billed for the next cycle. You'll still be able to use the Pro features until the 1st of the next month.