Why Did Barack Obama Give Up His Law License?

Why did Barack Obama give up his law license? Was it the annual fee he didn't feel like paying? Was he under investigation by the ARDC,ever? Anyway, here's the results:

ARDC Lawyer Search Results from the ARDC database last updated as of June 3, 2011 at 1:15:21 PM: for the following terms: Last Name: Obama, First Name: Barack, status: All, City: Chicago, State: IL, Country: usa

Your search terms do not match the record of any lawyer licensed in Illinois.

As you might guess, most people who go to law school and pass the bar don't give up their law license even if they are no longer practicing law. All that hard work and he gave up his law license. Same with Michelle Obama. Imagine that.