If you jailbroke your device using Pangu and didn’t check that box, then you need to read no further. You’re perfectly fine. But if you did check the box — intentionally or not — you need to follow the below instructions to protect your device:
Add Karen’s Pineapple Repo at cydia.angelxwind.net/
to your Cydia/APT sources (Manage→Sources→Edit→Add)
Install Complete PPSync Remover (net.angelxwind.completeppsyncremover) from Cydia.
Remove PPStore from Cydia.
Go to Settings→General→Profiles and remove the 25pp certificate. If you don’t see a Profiles section, or if there is no 25pp profile, that is okay. All that means is that PanGu never installed one.
You’re done. And yes, Complete PPSync Remover restores/Library/LaunchDaemons/com.apple.mobile.installd.plist
If you want to, you can uninstall Complete PPSync Remover.