You could do so in the number of speaking engagements you obtain or in how much you get paid for them after release of your book, for instance. (magnoliamedianetwork.com)
I'm so grateful to all of you for the support you've offered as I've written and released each of my books over the past couple of years! (theinspiredroom.net)
For the writer, it can take more work and administration to manage more than one digital release of your book. (adazing.com)