The Patent and Copyright Clause of the US Constitution (Art. 1, sec. 8 cl. 8) grants Congress the power to promote the progress of science and the useful arts by securing to authors the exclusive right to their respective original writings, for example songs with accompanying words and sound recordings.
In order to be able to enforce your exclusive right through an infringement proceeding (court case) and collect staturory damages(not to be confused with actaul damages), you as copyright song owner are required to have the song previously registered and deposited with the U.S. Copyright Office in Washington, DC. This registration is not free.
However, and this is a big however, under current law, compliance with the formalities of registering and depositing your songs with the U.S. Copyright Office (and paying a fee) is NOT required for basic copyright protection, because your original song is protected by federal copyright from the instant it is fixed in a tangible medium of expression (recorded and uploaded onto Ampslam for example) - without any regard to if your song bears a copyright notice: ©. Thusly, actual damages and profits can be awared to you without having your songs registered. In additon, I think the law does allows for 90 days after the infringment was uncovered for the song owner to register the song at the Copyright and still try to collect statutory damages.
Your original song is copyrighted if it is fixed in any tangible medium of expression from which it can be perceived, reproduced or otherwise communicated. In other words, by uploading your original songs on Ampslam, you are certainly fulfilling the fixed in tangible medium requirement since uploaded Ampslam songs are absolutely able to be perceived, (turn up the volume), reproduced (download the song) and otherwise communicated (stream the song).
The date you upload your songs onto Ampslam is kept in our data base as more proof of when you wrote/recorded you music.
By no means is Ampslam a substitute to registering your songs with the US Copyright office! No way! Here is the link to the U.S. Copyright Office for more information. If you have the money, go get your songs officially registered. You can do it on line. Ampslam helps bring your song out of your head and onto a fixed tangible medium from which it can be perceived, reproduced and otherwise communication.