The internationally recognised competency units remain current as long as the international standard they align with remains unchanged. This is normally for around 7 or so years. When an international standard gets updated, a short transition course is developed to ensure people remain competent.
If you wish to register with Exemplar Global as a certified auditor and it has been more than two years since you have gained your auditing competency units, Exemplar Global will simply ask you to complete a short exam for you to demonstrate your competency.