Actually, the exams are valid for licence issue for 2 years, you have to pass them all within an 18 month window (approximately).
An applicant shall be deemed to have successfully completed the
theoretical examinations for the JAR-FCL PPL(A) when awarded a pass in all of the ... examinations within a period of 18 months counted from the end of the calendar month when the applicant first attempted the examination. A pass will be accepted for the grant of a JAR-FCL PPL(A) during the 24 months from the date of successfully completing all of the theoretical knowledge examinations.