The US Copyright Office requires anyone that streams musical content on the Internet registers an Initial Notice of Use form and pay a $25 filing fee. This notice serves as your intention to use the statutory license under sections 112(e) or 114(d)(2), or both, of title 17 of the United States Code, as amended by Public Law 104-39, 109 Stat. 336, and Public Law 105-304, 112 Stat.2860.
In 1998 the Digital Millenium Copyright Act (DMCA) was signed, granting a performance right in the digital transmission of sound recordings. Simply put, the copyright holders of the performance of the musical work were not entitled to a royalty for the digital transmission of this performance. This meant more money to be paid by terrestrial radio if they streamed.