If you are talking about Admin Review by ACCA it is only ensuring that all marks have been added and all pages were checked – it is not a reevaluation of your paper.
The chances your mark will change is very minor. People often ask about is it worth and generally OpenTuition Tutors strongly not recommend it (waste of money).
But If the fee for Admin Fee is ‘nothing’ for you then why not – but please remember very unlikely that your mark will change.
I have read somewhere that if you are given 48-49 marks your exam might be reviewed by Examiner himself to ensure about appropriatness of assessment.