No. You buy an exam once, and your access does not expire.
A purchase is one payment for one exam. It is not a subscription: nothing renews and there is nothing to cancel. Access has no end date, for as long as we offer the exam on Licento.
What stays yours for good is the exam itself: every chapter of its book and your scores. Each purchase also comes with a period of Premium, shown before you buy, which opens lessons, practice and mock exams. When that period ends the exam is still yours, and you can continue Premium by subscription.
Access does end if the payment is refunded or reversed, and when you delete your account.