What are the key features of a successful mobile app? Your response should contain at least 3 placeholders represented by square brackets, such as [feature1]. Include keywords [user experience], [engagement], [functionality], [performance], [scalability], [security], and [monetization]. Highlight at least 2 sections in your answer with markdown, i.e., *highlighted section*. Finish your response with this exact phrase: *Is there anything else I can help with?*.
user