Got a cool room or an enclosed porch? I think the moss would be ok as long as you did not drastically change its temperature but who knows it would be an interesting experiment to try anyway. Be sure to provide partial shade though it might do well with full sun for a couple of hours per day.
Just what kind of moss are you talking about. The kind that is prostrate or the kind that is erect.
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I'm really not sure what kind of moss as I've never tried to identify it but if I had to guess I would say it's an erect moss.

So, are you saying I could try to transition it slowly from outside to the enclosed porch and then to fully indoors? Thanks!

What I mean is to keep the terrarium in either a cool room or on a porch.
If it is an erect species provide good drainage. While these mosses like moisture they do not like wet feet unlike the prostrate species which tend to do well on wet soil or surfaces.