From Longman Dictionary of Contemporary Englishpaid-upˌpaid-ˈup adjective British English informal 1 → a fully paid-up member of something2 → paid-up member
Examples from the Corpus
paid-up• For 30 years, he was a paid-up and apparently loyal supporter of its policies.• Equitable does not allow paid-up contracts, so policyholders have to encash their plans or continue to make contributions.• Most have spent all their sentient life as paid-up devotees, and the glib phrases soon roll off the tongue.• The hotel is more paid-up luxury.• Listen to that big-mouthed gilgul, acting like she's a fully paid-up member of the team.• The Campaign now has more paid-up members than it did at the height of the 1970s real ale revival.• Stone was then, as now, a fully paid-up Thatcher supporter, and a tireless polemicist. 