Adobe: The Psychology of User Offboarding

 It states that people tend not to change the things that already exist and are happening in their lives. 

Many companies use this to their advantage, for instance, having zombie customers (people who pay but don't use the software)

 Don't use unjustified discounts because it creates distrust in your users. It makes them cautious of the orginal price and trains them to always look for the cheaper option