Elon Musk's signature is highly sought after, but notoriously difficult to obtain. His public appearances are very rare and he travels with a military-ops level security team, which is expected as Mr. Musk is currently the richest person in the world. He is and will continue to be established as one of the most important figures in modern history and subsequently, the value of his signature continues to skyrocket (pun intended), and will even more so after commenting that he is "done signing" autographs.
The signature has been examined and pre-certified as authentic by AutographCOA (reference #PC111569), third-party authentication company comprised of industry-recognized authorities who specialize in the authentication of modern Hollywood, political and music autographs, and will come with a full letter of authenticity. The certification can be referenced by visiting AutographCOA's website.