Unlicensed means without the official permission paper you are supposed to have. It works two ways. It describes a person: an unlicensed driver has no driving licence, an unlicensed doctor is practising without the qualification the law requires. And it describes a business or activity: an unlicensed taxi, an unlicensed guesthouse, unlicensed street trading. Both carry the same weight — this is not allowed, and someone could be fined or shut down. It is a legal and news word, formal in tone; you see it in newspaper reports and government notices far more than you hear it in conversation, where people just say 'he doesn't have a licence'. One special use worth knowing: in Britain, a place that is 'licensed' is legally allowed to sell alcohol, so an 'unlicensed restaurant' does not mean an illegal restaurant — it means one that cannot serve you wine or beer, and often you may bring your own. In computing and publishing, 'unlicensed' software or an unlicensed copy means one you have no permission to use — a pirated copy. The word is almost always used before a noun.