I'm right now on Beta 2 of Mac OS X 10.11 "El Capitan" (15A204h)
The Mac App Store wants me to update to Beta 3 
I know that the latest Beta is Beta 7 (15A263e)
Redeeming the code for Beta 7 doesn't work.
It seems that this is the same code that got me Beta 1
Image from Purchases section of App Store:
And I cannot see in "Purchases" section of App Store Beta 7 available.
Is there a way to upgrade from Beta 2 (or any earlier version) to Beta 7 directly. Without having to upgrade 5 times?
Best Answer
Update incrementally to Beta 3. And you will get immediate update to 7th beta (So they've done combo update from 3 to 7 - nothing more is known)
This is what is shown in App Store on Beta 3.
After update: