Spain if you become a resident of Spain you must exchange your UK license to Spanish within 6 months and that’s time is being reducedThere is no limit to the duration that any EU issued licence can be used in the EU, if you become resident in an EU country there is no requirement to exchange a GB licence for one issued in the new country. It only becomes an issue at renewal where DVLA will not issue to non UK residents. As for vehicle registrations, it is possible for someone from the EU to bring their vehicle here to the UK and drive it on the originating country's plates whilst resident here providing they are resident only for a defined period ( fixed work contract, student etc)