Get your taxes done using TurboTax

Do you mean prior year product key?   Did you buy a prior year Desktop program?   Or have a 16 digit License Code?  If the program download is not listed in your Online account you may have to call in.   What did you buy and where?  What year?

To enter a License Code you first have to download the program on a full Windows or Mac computer.  Then install it.  During the installation it will ask for the code.