Lost License Key

I have the pro version installed from a purchase of pro version of ccleaner at Frys. I can't find the envelope with the license key on it put have it installed on a computer.

How can I retrive the license key from the computer I have it installed on?

Hi, welcome to the forums. As you have a pro version of CCleaner, please contact Piriform support via support@piriform.com

They will be able to help you further.