What is "Close Program After Cleaning" Advanced Option...?

I see this option, but don't know if I should be using it?-

I don't wipe free space/MFT, and using latest CC version.

tick that box, click Run Cleaner, when finished, CCleaner closes itself.

tick that box, click Run Cleaner, when finished, CCleaner closes itself.

Does this also allow me to also Registry clean, which I Always do After file cleanup?

No, registry cleaning is completely manual and must be user invoked.