when does the customer make the paiment and when do you verify all paiment have been done ?


Please if it's in close out, specify if it's part of administrative closure or contract closure

I guess it should be contract closure and administartive closure happens only one.

all payments are done in close procurement process.

If the project is closing then also payments are made in close prcurment stage as project cannot close without these step.

(Refer to page 387 in PMBOK)

As far as I know, the payment should be get done before ending the best essays project. Otherwise without the payments project cannot be closed. So you have to check it well before the time I guess.