I would like to say a quilt is not finished until it gets a label and a hanging sleeve. Most of my quilts do have labels.
Why put labels on your quilts? Well, for everyone to know who made the quilt, why, for whom, who quilted it, where was it made, when was it made, what pattern was used to make it, or was it an original design? What kind of fabrics were used, where they from a kit? or did the maker selected them herself? What kind of batting was used and anything else you can think of.
I use labels that are commercially made or sometimes I make my own.