Welcome to the Magix user to user forums, so not a contact for any Magix staff and confidential data, like your order number, should never be posted to a public forum like this one. Hence, I have edited your post.
The number you quoted is NOT a serial key, it is your order number for Magix Sound Forge, presumably Audio Studio 12.6. You need to find the original email confirming your purchase, it will include the serial key. Since you quoted the order number from that email you should be able to find the serial key!
If you cannot find that email and you have previously registered and activated the product, go to your Magix account, log in, go to My products and find the listing for SF 12.6. The serial key will be listed there.
If you do not ahve the email and cannot access your account you will need to email email@example.com with FULL details of your original order and ask that they resend your serial key.
Seasons Greetings and welcome to the Magix Sound Forge users community @NELIO
Firstly there is no "Sony Sound Forge 12" The last Sony Sound Forge was 11. I sincerely hope you do not have a hacked version, which we can not help you with. That said, if your Magix Sound Forge product was previously activated/registered, log-in to the Magix Service Center to verify your activation serial code. Your product's serial code and the email address are paired so you must use the email address that was used when you originally registered and activated the product. The email address you use to log-in to this forum may be different. If none of the above helps to resolve the issue, email Magix Customer Service: firstname.lastname@example.org
When did you purchase Sound Forge 12 and was it combined with other Magix software? Magix only sells the current versions directly (which is SF-16). Third-party sellers often have legacy and current versions for sale. If this is the case, a 'voucher' code is usually included when purchased for download on-line. When redeemed, Magix emails a link to download the product and a serial code to activate it. If SF-12 was purchased and registered previously, the installer can be downloaded from the aforementioned Magix Service Center or Magix Download Center.
MAGIX Software GmbH has faults, but dishonesty ain't one of them and would never blatantly rip-off folks.