While there are legal, albeit complex, paths for a dedicated few to reactivate an old license or purchase a used one, these options are not practical for the vast majority of users.
Recovering a lost serial from an installed copy Sony Vegas 7 Serial Number
Because the original Sony servers are offline, you must use an method through the current rightsholder's (Boris FX) support portal. While there are legal, albeit complex, paths for
The only safe way is to purchase a legitimate license. But since Sony sold its creative software suite, including Vegas, to MAGIX in 2016, getting a key is now difficult. You can try: While there are legal
Legacy software has no support from Sony or MAGIX (the current owners).