If you want to stop users from logging in from multiple machines at the same time, use the instance profile parameter: login/disable_multi_gui_login
Go to Transaction RZ10
–> Select the Default Profile
–> Click radio button for Extended Maintenance
–> Clicck Add then type: ‘login/disable_multi_gui_login’ in the parameter box.
–> Value *
However if you want particular users to be excepted from this rule you could set up the parameter: ‘login/multi_login_users’
The users against this parameter will be allowed multiple logins. This applies to dialog logon type only. It does not apply to system logons that occur using the Remote Function Call (RFC) or to logons via the Internet Transaction Server (ITS).