If you are buying software or programs from sellers other than the official distributors, the chances are that you will get either: a virus, key-logger (software which records whatever you are typing on your keyboard), a fake version, or even an auto-calling software.
This latter one is extremely dangerous if you have your computer connected to the phone. The software is programmed to call several hot-line numbers automatically, getting your phone bill to thousands of dollars, which go into the scammers’ pockets.
Sometimes, whatever you are buying needs a serial number that you’ll never get – so if you are considering purchasing software from places other than the official ones, don’t be surprised if you lose your money (or maybe your credit card access).