I have bought the steam edition of Vegas Pro 14 and was looking to upgrade to the 20th version. This isn't possible through steam as there is no serial number present in the help>about section and no upgrade available through the market itself. Is there anyway I could get an upgrade another way?
... there is no serial number present in the help>about section ...
That's right. Steam versions of Vegas Pro do not have serial numbers because registration/activation is via your Steam account. Have you asked Steam about their upgrade policy - if they have one - to the Steam version of vegas Pro 20?
Otherwise, you might want to contact MAGIX at sales@magix.net and ask if they can offer a pathway to the retail non-Steam version of Vegas Pro 20.
As @Dexcon writes. From MAGIX Sales Dept. in May 2019: "Steam customers do not have a serial number for the MAGIX account. So, they need to check if an upgrade is available in the Steam Store or contact MAGIX Customer Service (infoservice@magix.net) to receive a personally upgrade offer."
I'd personally try contacting Magix, then you will not have to worry about upgrade offers again.
We occasionally create bundle offers (VP 19 and VP 20, for one low price) which are used as a substitute for the lack of any upgrade model on the Steam platform. We've offered these in the past for VP 14, but we can no longer sell VP 14 due to licensing changes with some of the codecs in that product. As a result, it is not possible to produce a bundle for VP 14 which would include VP 20. The ideal thing have done last month was to buy VP 18 on Humble Bundle and then purchase and upgrade to VP 20 on the VEGAS website.
As also mentioned, Steam keeps all user information related to purchases for themselves, and as such, we do not have any way of being able to verify a customer who has purchased via that platform in order to provide a upgrade price.
I will pass down this request to our team which handles the Steam store to see if we can find some creative way of upgrading VP 14 Steam users, of which we have a large number...but I cannot promise that anything will be able to done in the short term.