Have a field for the IP address on the user extended properties entity(you have to create yourself) and record the last IP that the User logged in. If you want to have a log history, you need to have a third entity that records various ips for the user instead of having just the user extended properties entity. In this third entity, you will have the id of the extended properties entity and the user id from the User entity and the IP field.
Then you can get the IP using the GetIp, check the below post to see how to get the IP.
https://www.outsystems.com/forums/discussion/63966/how-to-get-user-ip-in-outsystems-reactive-app/
Kind Regards,
Márcio