How to find your windows 98 key (from your registry) - or just use keyfinder (magic jelly bean)
HKLM\Software\Microsoft\Windows\Current Version\Product ID
In the results that appear in the window on the right, locate the ProductID.
The numbers and letters on this line represent the Windows 98 product key. The product key should be formatted like xxxxx-xxxxx-xxxxx-xxxxx-xxxxx - five sets of five letters and numbers.
Write this product key down exactly as it is found here for use when reinstalling Windows 98.
If your system was purchased with Microsoft Windows pre-installed, and you have not reinstalled it or upgraded it yourself, the product key found by the steps on this page will only find the generic product key that your computer manufacturer used to install the operating system. This product key will not work when attempting to reinstall Windows. In this case, you must use the unique product key that is on the sticker attached to your computer case.