You can try Habitica out for free, but they do offer 3 different subscription plans.
Monthly ($4.99/month)
Trimonthly ($14.99/3 months)
Yearly ($47.99/12 months)
Subscribing to Habitica gives you added benefits to help you in-game. Some of these benefits include exclusive in-game items, monthly in-game gifts, the ability to export data, and more.