I have downloaded Movie Studio 13.0 Platinum on another laptop and it won't accept the authentification code previously used, I tried with my account at Sony and was refered to your website. I still have my previous code.
The activation code should work with the original email address you used to activate with Sony Creative Software
What is the error message you get?
You probably need to contact support as this may or may not apply: "Older versions of Vegas Pro [Movie Studios as well] than 14.0 are licensed under a system (as previously used by Sony) which permits use on multiple computers by one user; after an unspecified number of installations on different or updated PCs you may need to contact support to reset your "installation count".
(Don't know if this is related but last week I needed to uninstall/reinstall my (last Sony/SCS build of) MS Platinum 13 on both of my machines. Surprisingly (as it worked only a couple of days earlier), the software refused to open and I was directed to the old Sony-era form to put in the code. After reinstalling (the same build) I was able to do that succcessfully and MSP 13 opened correctly again. Note that the other SCS-era programs including VMSP 10 to 12 and the last SCS build of VPro 13 did not or do not currently have this issue.)
I have tried all I know. It asks for serial number of laptop, and ID, is that for the one I have recently installed or the old one, not enough information.