Is my certificate valid if I dont pay membership fee

Hi all, wondering if someone can clarify the case.I have recently found out that non of mine work colleagues with AAT qualfications pay membership fee after they completed all exams/papers. My manager who is financial accountant (and has not got anything else except AAT) said she is not paying anything as she is not working in practice and doesnt bother about full member status. She stated as she passed all her exams her certificate is still valid without membership subscribtion.
Is that correct? Is that a pain to renew your membership if you will need it? At the moment I am waiting for the reslut of the last exam and not sure now if I need to apply for MAAT as cannot see any benifits of job promotion or pay rise lol