What is the name of the Platform parameters that controls how long a password will...

 The name of the Platform parameter that controls how long a password will stay valid when One Time Passwords are enabled via the Master Policy is Min Validity Period. This parameter defines the number of minutes to wait from the last retrieval of the account until it is replaced. This gives the user a minimum period to be able to use the password before it is changed by the CPM. The Min Validity Period parameter can be configured in the Platform Management settings for each platform that supports One Time Passwords. The default value is 60 minutes, but it can be modified according to the organization’s security policy1. The Min Validity Period parameter is also used to release exclusive accounts automatically1. References:

1: Privileged Account Management, Min Validity Period subsection