The question of whether you should glue underlayment down to a subfloor may come up if you are installing flooring for the first time. You want to make sure you have a solid foundation for your new flooring. You would think this would extend to your underlayment.
Should I Glue Underlayment Down?
No, you should not glue down your underlayment. Underlayment is is a floating material, the same as your laminate flooring. In most cases, you should not glue or nail your underlayment down. You should always check with the installation instructions of the underlayment for proper installation instructions first.
Learn more about installing underlayment here.