What happens after app uninstall?

When you uninstall the app, all price changes that you've made will stay. All your tasks and sales will be saved in the app for 2 months after uninstalling. During that time you'll be able to re-install the app and rollback any task or disable sales. 

After 2 months, all tasks and sales data will be permanently deleted and you won't be able to roll back any price changes.