One of the main purposes of creating single European market was free movement of people, goods, services and capital between all 28 member countries of European Union. You may choose to provide services in another EU country without establishing yourself there permanently. If you comply with the rules of the profession or trade that apply in one EU country, you can offer those services anywhere else in the European Union.
Trade within the EU has risen by 30% since 1992. The absence of border bureaucracy has cut delivery times and reduced costs drastically.