When you downgrade a package or uninstall the app, all of the data - which was created by the features belong to that package - will be frozen.
E.g. You was previously on Advanced plan and you have created a popup with advanced settings. Then you decided to downgrade to Basic plan which does not include the Popup feature. That would result in the Popup being frozen and would not display on your store anymore, you can no longer edit those data either until you switch back to the Advanced plan.
*IMPORTANT NOTE: Your data is archived up to 3 months before being removed forever. During the archiving period, it can be restored fully anytime when you re-install the app, or re-open your store.
If you need any assistance, please let us know via our live chat or contact us at firstname.lastname@example.org