What do I do if I lost my Serial Number / License Key?
Please submit your request at questionacharge.com with the invoice link or Order ID number.
If you need to re-activate Capture One or activate it on another computer, you can find your license key in your Capture One account as well. Simply log in to your account on captureone.com, navigate to the Manage licenses section, choose the product you need and click on it. In case you have not used the license key for activating the software yet, find it in your FastSpring account.
When the license was purchased from an external vendor or reseller, you should contact them regarding the license key.
For more details, check the article - How to find Capture One License Key.