Hi!
Answering the question posed in the title: Of course, it can go bad!
You can only decide it by tasting, IMHO.
If it’s not satisfactory, then down the drain, etc.
At 1.5 years old, the flavor only weakens slightly at most… spoilage isn’t typical. (Especially not in that sense…) But tasting will tell. My 2-year-old room-temperature mixes are also perfectly fine.