Select the license key text from your email or the web page where you generated it. It will be multiple lines long and start with *r. Select the entire multi-line block of text.
Then hit Ctrl+C to copy the license key text to your clipboard.
If you haven't yet downloaded and installed the program of ours that you are interested in activating, do that now!
Start the program on your computer that you are trying to activate and go to the Help menu.
Choose the menu item labeled "About" or "About/Enter License Key".
An About Box dialog window will pop up showing some information about the program.
Click the button on that dialog window labeled "Enter New License Key" (or something to that effect), to show the edit box where your license key will be pasted.
If there is an older existing license key already shown in the edit box, select it and hit the Delete key.
Now put your cursor in the edit box and hit Ctrl+V to paste in your new license key text (if you forgot to copy your new license key to the clipboard that's ok, go copy it now from your email or web page and then paste it).
Click the OK button to accept the new license key.
To make sure your new license key was accepted, open the Help menu and select the About box again and you should now see your name and info in the about box.