@sidmsmith said in Expression Evaluation - Last Seen Date/Time:
If I don't hear back within a few days, I will go ahead and update this as Solved.
your solution is correct. This code will give you the ability to use it in notifications (ie: Door left open for 5 minutes) or when you want to do things programmatically (ie: house is away since 12 hours, do that, 18 hours, do this, etc).