A quick answer, then back to your trip.

Your latest changes remain safe on the device where you made them, even while offline.

1. Confirm both devices use the same Apple Account for iCloud.
2. In Settings, confirm iCloud Drive is on and PackOnce may use iCloud.
3. Open PackOnce on both devices briefly on a reliable connection.
4. Make a small edit, such as renaming an item, then check again.

Do not delete the app as a first troubleshooting step.

Open PackOnce, go to Settings, and choose Restore purchase. Use the same Apple Account that made or received the purchase through Family Sharing. If Apple reports a billing issue, visit Apple Support.

That is intentional. Lifetime access unlocks creation of additional trips and saved lists. PackOnce never puts existing content behind the purchase screen.

Checking an item changes only its packed state. PackOnce changes order only when you explicitly reorder a list, so you never lose your place.

Choose Undo in the message at the bottom of the screen. Undo remains available for five seconds. If the message has gone away, add the item again in its section.

Open a trip and choose Share. You can send the entire list or only unpacked items. PackOnce creates a plain-text copy and opens Apple's share sheet; it does not create a live shared list.