The free trial
Three days on the yearly plan, cancellable throughout, with the conversion date shown before you start.
The yearly plan starts with three days free. Before you confirm, the store shows the date the trial converts and the price it converts to. Cancel any time during the three days and nothing is charged.
The monthly plan has no trial and can be cancelled at any time. Settings → Subscription shows your status: Trial until a date, or Active until a date.
The trial is offered once per store account, which is Apple's and Google's rule, not ours.