EDIT: in fact I'm the fool in this case, so don't bother reading the rest, except if you have nothing better to do. Dropbox is simply guilty of not being clear enough for dummies like me. It wasn't a stupid marketing trick.
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Hi, I have a Dropbox account since.. a loong time.. I got the 2GB free, then I've referred the maximum number of people so that I got 21GB free, then I bought a Samsung device and got 48GB free for 2 years, it was... well nearly 2 years ago..