The Verge posts a quote from a Dropbox email that was sent out to their earliest users:
"Let’s be real -- you’ve got a ton of cred for being one of the earliest Dropbox users on the block. For sticking with us for all this time, we’d like to give you your 25 GB subscription for free!
No fine print, no catches. You’ll no longer receive a bill for your current Dropbox account. It’s yours for good!"
So awesome, those Dropbox fellows are.