Since the driver's license debate has been going back and forth for a while, I feel compelled to add a real life example to the discussion.

My mother received her driver's license in Paris in the late 60s. In the early 70s, my parents returned to Germany, where she missed her window of opportunity to trade her French license for a German one. Therefore she continued to use her French license without ever having to show it, until, after 30 years, she was involved in an accident (not her fault).

Police was called to the scene, informed her that the license was no longer valid, but told her that laws had changed and that she could get a European-format license in France, which could then be traded for a German one. They also gave her a verbal warning, but no fine and they did not mention the license question in the accident report.