Citizens of the EU / EEA / Swiss Confederation and their family members may carry out commercial or economic activities in Romania under the same conditions as Romanian citizens.
For professional Activities you will have to provide the followings:
1. standard application;
2. identity card or passport (original and copy);
3. proof that the applicant may exercise the professional activity – authorization or notice (original and copy) issued according to the special law;
For more info: http://igi.mai.gov.ro/ro/content/cet%C4%83%C8%9Benii-din-statele-uesee