When to Replace Clutch?

I'm installing a used engine that likely has at least 150,000 miles on it in my '93 318i. I'd appreciate advice on the typical clutch lifetime. I'm not sure whether or not to replace the clutch, pressure plate, and bearings before I install the engine.

It depends entirely on A) the driving style of the previous owner(s), and B) if/when the clutch and related parts have been replaced at some point in the car's history. You can kill a clutch in a day if you roast it by applying too much gas and releasing the clutch too slowly, or they can last 150-200k miles if the driver knows what he/she is doing. If you have 150k on the original clutch, I would recommend replacing it while you have the transmission out.

Thanks for the advice ZeGerman.