Does depression has link with lichen planes? Can it heal in 18month if depression still exist?

Yes - link. According to dermatology. 2001;203 (4):303-7. 'anxiety and depression as risk factors for oral lichen planus' - there is a link between lichen planus ; both anxiety ; depression. This means it is a factor - but doesn't necessarily mean that it can't heal if those symptoms/ conditions are present..