I do not label my quilts 100% of the time, but I do try, even quilts I plan to keep for myself. I've made a lot of quilts over the years and although I thought I could remember when I made them, I don't. It's nice to be able to look at quilts I've made 10,20, even 30 years ago, check the date and realize how much my piecing and quilting have improved over the years. My quilts are not heirloom quilts, with the possible exception of the family reunion quilts I make every 2 years, but I look at them as my legacy, and I know for the most part they will be treasured and used. I usually write with Pigma pens on white or muslin fabric ironed over freezer paper, which makes it easier to write on, then I remove the freezer paper after sewing the label on.