You should not need a backup disc for P2Go13. The download should be in the Download folder. You can back it up for free. Just copy those installation files to an external backup hard drive, usb stick, or dvd disc.
If you want a backup disc then all you have to do is check the box for back up disc $7.14 when ordering the software. See this link:
https://shop.cyberlink.com/c/shop?curr=USD&cntr=&ml=EN&LOCALE=en_US&OFFER_ID=9112WD082103&AFFILIATE_ID=2581_1433_540&AM=1&ID=P11034930 . They do not sell the backup disc by itself.
For more information just contact Cyberlink support by phone or email. Here is the link:
https://membership.cyberlink.com/support/customer-services.do .