I am responding as a member of the International Association of Amateur Heralds.
Unless you are descended in the male line from a person who possessed agrant of arms, or recorded assumed arms, or you have yourself received a grant or have assumed and recorded unique arms, the answer is no. If you have purchased a so called “family” arms from some on-line site, or a mall kiosk, what you have is simply a certificate showing the arms of someone with the same surname you have, not your arms at all. As a resident of the US it is perfectly acceptable to assume your own arms, provided they are unique and designed in accordance with the accepted rules of heraldic design. Check my web site at www.larrylsnyder.com