Dustly Unlimited
Dustly is free for up to 5 tasks, with every feature. Dustly Unlimited removes the limit with a single purchase.
The free version
Settings shows how many of your 5 free tasks you use. When you have 5 and tap "Add task", Dustly offers the unlock instead of the form. Your tasks are never removed.
Unlock
Tap "Unlock for $19.99" and confirm with the App Store. It's a one-time purchase, not a subscription, and works on iPhone, iPad and Mac. Prices in other countries are set by the App Store.
Restore or share the purchase
On a new device, Dustly usually finds your purchase by itself. If not, tap "Restore purchase" in Settings, signed in with the Apple Account you bought it with.
Dustly Unlimited works with Family Sharing, so people in your Apple Family get it too.