You may be able to purchase it on eBay or Amazon.  Here's a link to products on eBay
<a rel="nofollow" target="_blank" href="https://www.ebay.com/sch/i.html?_nkw=turbotax+2013">https://www.ebay.com/sch/i.html?_nkw=turbotax+20...>

Ok, thanks. So I  can't file my 2013 with them. I filed an extension

Not sure if you can still get updates to the 2013 TT software.
If the return is simple enough, you can always download the forms and instructions from the IRS website and fill in by hand.   Professional preparers have access to prior years updated software, so if its a more complicated situation, you may seek out a local tax professional.