No you don't register accessories. See this Locate the Service Tag of Your Dell Laptop | Dell US  
Hello,  Seeking for answer about my Stylus Pen PN350M on my Inspiron 5410 2in1. Do i need register my stylus pen? where can i find service tag number on PN350M stylus pen? and where to register it? Any Helps? regards. er  
Do I Need Register my Stylus Pen PN350M for Inspiron 5410 2in1