"Login attempts to lock session" is a GAM Repository property which determines the number of times a user can try to login, until the session is blocked and he needs to close the browser and try again.
The GAMRepositoryConfiguration web panel (located in GAM Example folder) is an example where this property is used.
The way to use it in GeneXus code (by using the GAM API) is the following:
&Repository.LoginAttemptsToLockSession = &LoginAttemptsToLockSession
Login Attempts To Lock User
GAM Repository features and properties