Gatsby stopped hosting the parties in Chapter 7 of "The Great Gatsby" because he didn't need them once he and Daisy began their affair. Gatsby had thrown the parties previously in hopes of drawing Daisy to one of them because of their extravagance.
Gatsby also fires all of his servants in order to prevent them from leaking secrets about his affair with Daisy. Gatsby replaces the servants with Mr. Wolfsheim's men, which alludes to Gatsby's inability to escape from his criminal past. Even though Gatsby has reached his goal of having Daisy, he still has not realized how the illegal means that he used to acquire his wealth eventually become his undoing.
This is realized later in Chapter 7 when Daisy, Gatsby, Nick, Jordan and Tom go into the city to escape the heat. In the hotel, Gatsby asks Daisy to tell Tom, her husband, how much Daisy is in love with Gatsby. Daisy refuses and Tom realizes that his own "old money" power is more appealing to Daisy than Gatsby's illegal "new money." Daisy's belief that love is derived from wealth is shown when Gatsby describes her voice as "full of money" and when Daisy compares Gatsby to an advertisement which alludes to Daisy's materialism.