Why Didn't I Have to Insert a Serial for CS4?

Trial Version

• Adobe Systems allows you to download, install and use its Creative Suite 4 for 30 days. This trial period gives you a chance to decide whether the applications meet your needs and deserve your investment. If you're new to graphics software in general or Adobe's products in specific, this free trial lets you dive in to the applications before you invest your money in a software license. The trial-software installer won't ask you for a serial number because it knows you don't have one.
  
  

Upgrade

• If you install Creative Suite 4 as an upgrade from CS3 or another qualifying earlier Adobe product, you'll need to enter two serial numbers to access your software: the number from your prior version and a new serial number for your upgrade. You can save at least half the hassle of that routine, however, if your preceding version of the Creative Suite remains installed on your local hard drive. Adobe's upgrade installer searches your drive for evidence of a qualifying product and obtains its serial number, saving you time.
  
  

Volume License

• If you or your employer purchased a site license authorizing the installation of multiple copies of an Adobe product, none of those individual installation procedures require you to enter a serial number. Volume-licensed Adobe products use special network-based monitoring software to track the number of copies in use and prevent more than the licensed quota from launching. Similar behind-the-scenes monitoring means that software installations automatically serialize themselves to the volume license.
  
  

Already Authorized

• If you've previously installed and authorized the Adobe Creative Suite on your system, then removed the product without deauthorizing it, your computer may retain the authorization. If you've changed your system configuration -- upgraded a hard drive or video card, for example -- your authorization won't survive the hardware alterations and you may need to contact Adobe Systems to be able to complete the installation procedure.