Pocket Lists supports realtime import from the Apple's basic Reminders app.
The import is updated every time you launch the app and every time the iOS throws an event that a new event/task has been added on the Reminders app side.
Pocket Lists only reads data from the Reminders, and does not write anything back. It means that you may freely edit and delete Pocket Lists lists and to-dos that were imported from the Reminders, and your Reminders app data won't be affected.
Head on to Settings > Import to enable or disable import from the Reminders.
Feel free to disable and re-enable the import any time. It will only affect the import auto-update feature. All the data that were previously imported will stay in the Pocket Lists app unless you manually delete it.