What happen if I uninstall the app?

If you uninstall the app, you will not be able to edit the metafields anymore.

More importantly, if you have uploaded any images directly through the app (either in the dedicated image field type, or through a rich text editor), they will automatically be scheduled for deletion 21 days after you have uninstalled the app.

If you want to avoid this, you can always re-install the app before those 21 days, and everything will be restored automatically (both your groups and images)!