PDF Stamper by Tips and Tricks HQ Support Portal › Forums › WP PDF Stamper › WP PDF Stamper Troubleshooting › PDF Stamper Tagged: invalid, license, license key This topic has 23 replies, 7 voices, and was last updated 9 years, 6 months ago by admin. You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In