You should QT nems.
From personal experience, Nems, can carry pests.
In my case, they were pycnogonidas (Seas Spiders). Juveniles are hard to see but they will plant themselves on soft corals and invertebrates like anemones and suck out their juices. Observe the anemone for several months in QT and if all appears good, then go ahead and place it in your display tank.
The pycnogonidas take time to grow but eventually the anemone will start to curl/flinch on the sides in which the pycnogonidas are attached/infested too.