Registration for professional

There is no need to take n ay registration as such.  For your case, You can start a  business as a proprietorship business, with a PAN card in your name.  For your tax returns, file iTR 4S (sugam) on annaula basis.  As for in depth details, look if your business turnover i.e collections of money exceeds 9 lakhs you must have a service tax number.  For your case the category of service tax will be  Business Exhibition Services.  Very soon we are gonna have GST which will replace service tax, so as of now, take a service tax number from www.aces.gov.in

thats all , file two returns, one for income at end of financial year and twice for service revenue at end of six months in a fin year.  The first return is relaxed, you can file or skip it.  if you generate money, then decudt service tax at 14.5% and depsoit the tax in govt account.  thats all I can dish out.  hope you earn good money