If you download and install trial version of Kingsoft Office products, you will need to enter serial number when install them. After entering the serial number, the installation process will continue and you can enjoy the full features of Kingsoft Office (or individual products of Kingsoft Writer, Spreadsheets, Presentation). The serial number is stored within the product management center, and you can save it in a safe place if not already done so.
In any of the three office suite components, Writer, Spreadsheets or Presentation, you can easily find the Help menu from the toolbar. Click it to select Product Management Center from the drop down list.
You can add new serial number to the list or delete existing ones. One single-user serial number for Kingsoft Office products can be used on three computers, which means if you want to use the same serial number on a fourth one, you need to delete it from one of the three activated copies. Simply select the serial number in above screenshot, and press Delete > OK.