Gamasutra –

Below are the results of Reflexive.com sales and downloads immediately following each update:

Fix 1 – Existing Exploits & Keygens made obsolete – Sales up 70%, Downloads down 33%

Fix 2 – Existing Keygens made obsolete – Sales down slightly, Downloads flat

Fix 3 – Existing Cracks made obsolete – Sales flat, Downloads flat

Fix 4 – Keygens made game-specific – Sales up 13%, Downloads down 16% (note: fix made after the release of Ricochet Infinity)

From the results above, it seems clear that eliminating piracy through
a stronger DRM can result in significantly increased sales – but
sometimes it can have no benefit at all. So what does that mean for the
question about whether a pirated copy means a lost sale? The decreases
in downloads may provide a clue to that

As we believe that we are decreasing the number of pirates downloading
the game with our DRM fixes, combining the increased sales number
together with the decreased downloads, we find 1 additional sale for
every 1,000 less pirated downloads. Put another way, for every 1,000
pirated copies we eliminated, we created 1 additional sale.