Trip Planner comes with your PRO membership, so the price is included with your annual subscription fee. It is also available with any free trial you subscribe to.
There are two membership levels to choose from.
Yearly - this one comes with a 7 day trial, if you want to "try" before paying. Once the trial is over, it's $35.99 chaged to the card you have on file when you sign up for the trial.
Monthly - this option is is charged immediately, one month at a time, with no free trial. $6.99/month with no commitment past the first month. Cancel anytime!