We are so glad you'd like to try out our premium subscription. We do offer a free week trial for this. The way this works is that when you pre-authorize a year subscription, the week trial is activated. If you decide to cancel before the trial period ends, the pre-authorized charge will be lifted/removed and you will not be charged.
Make sure that you select one of our purchase options that specifies the trial as some discounts are offered without a trial. Also note that any subscription that is shorter than a year does not include a trial.
Need further help? Please email us by going to "Send Us Feedback" in the settings menu of the app or writing to firstname.lastname@example.org.