The Product Control Code is an encrypted string of readable characters which contains lots of information about your license.
A typical Product Control Code looks like this:
___3NKAZZ9.ipG5l3+U57bG/Xd4CdBPM9d24pHvObJYFhqZNe
AfZtjD6+UuSaboJMkEIepKYmTDXcwyIer4yY42pgJSX5YD9T4
cnw4OSrHuJ0YIXbLchgMhyA3zp6D9KyzLyvI6hs+vl5kuMeKk
eRbjDxhG7ijlv9qRjWZpfUppsvXCKbgyJJp83RKbJ//DqJf5d
5Ro85bn6Af2pBetREaOr3PBzensr5zbwV6mjSK+m28OutF9Ly
Ml8p2NybQ2Mg==___
The underline characters in the front and back are meaningless.....they just serve as endpoint's so you can easily cut & paste the string.
This Product Control Code will be emailed to you as a file or more commonly within the body of an email.
To enter it into the program you will select "Settings | License Information from the main program menu to display the following screen. All you need to do is cut and paste the Code into the entry area and then select the 
button.
After pressing the button and the Product Control String is properly decrypted the window will change to show this type of information:
Note that the "License Code" appears on the screen now. This is the code that is used with our web activation server.
At this point you can either continue with the evaluation or select [Product Activation] to finish the process.