For security reasons, Policy Manger will automatically disconnect from the Gateway after some idle time. It's 30 minutes by default. But it could be annoying if you have to login again just because you turn to something else for a while.
1. In Policy Manger, navigate to menu "File" > "Preferences" and set "Inactivity Timeout" value to 0
2. Navigate to menu "Tasks" > "Users and Authentication" > "Manage Administrative User Account Policy" > set "Gateway Session Expiry" to a value you prefer (1~1440 minutes)
For older version of CA API Gateway (9.0 or below), the menu path should be "Tasks" > "Manage Account Polices" > "Manage Administrative User Account Policy"