Product keys are distributed together with the software. Please check on the installation cd's package if it is there. If you don't find it, please explore the installation cd and look for a read me file in which the product key is normally stored. It should be on the installation cd.
In the case that you are unable to get the product key from the two mentioned methods, you will be compelled to contact the distributor or the manufacturer directly in order to get the product key.
Hope that the information provided proves useful.
Thanks in advance.