I'm not sure I understand the question, but here's my take on things anyways...
The updates that are posted are exactly that; updates that correct bugs and issues, etc. You're not downloading the actual program.
After all, the full blown Sound Forge program (I use 7.0) is not free; not even close to free. LOL
Sony puts a letter after the version number of a program, and that letter is the basis for updates.
Example: I bought ACID Pro 4.0b, and recently I downloaded and installed the 4.0f update; which was around 30 some odd MB.
And no, it didnt ask me for my activation code. The only times you're required to enter an activation code are...
1. Converting a demo to a full blown version.
2. Installing the full blown version for the first time.
And finally, Blue Bear Sound's colorful (and very funny) response is right. Basing a program's merit on the size of a download does come off as incredibly stupid. No offense.