Changed window names not saving

I think this is just me doing something wrong, but I can'f figure out what. Before I buy a license, I need to know tabs outliner will do one thing that I really need it to do: remember the new names I give windows. I have no trouble renaming them, but the next time I open my browser, all the names have gone back to "Window." With a lot of windows open, that can make it a real hassle to go through and figure out which one is which. 

I *know* this feature must work because no one else has mentioned it not working. But what could I be doing wrong?