Hello mengfei@co-mall.com,
The trial version activates only once per each unique machine. Learn more about the Fiddler Everywhere licensing through the following sources:
https://www.telerik.com/purchase/license-agreement/fiddler-everywhere
https://docs.telerik.com/fiddler-everywhere/introduction#trial-version
https://www.telerik.com/purchase/fiddler
mengfei@co-mall.com