By default LoadRunner /Performance Center agent service is running by local system account, how to use other account to logon the service
If you want to change the logon account, run services.msc from command line, and find LoadRunner /Performance Center agent service, go to log on tab of the properties, and then enable log on as this account and select the user that you want to use to start the service and input the password.
We recommend that user account that is used to log on as a service have the Password never expires check box selected in their Properties dialog box.
If account lockout policy is enabled and the account is locked out, the service will not start.
If the password of that account is changed, there is no way to change the password for LR/PC agent service logon account automatically, becasue it handles by MicroSoft, you need to change the password for LR/PC agent service logon account manually.
For more information about Service Logon Accounts, please check https://msdn.microsoft.com/en-us/library/ms677948%28v=vs.85%29.aspx