Anemones often shrink up for a few days after you move them. However, a healthy one will usually anchor itself quickly. Since they are all soft tissue they can get in and out of some very tight places, including parts of your filtration system. You need to be a bit careful here because they can sometimes cut themselves on rock or coral.
Sabae anemones can be tricky. Keep a close eye on it to make sure that it's healthy. A dead anemone can foul a system very quickly. They can also get very large, so make sue your tank is fairly large. All the usual stuff about top quality water, well established tank, and excellent lighting also apply to sabae anemones.
While they don't hunt you fish as such, anything that blunders into a large anemone may be eaten. I've had this happen to me a few times, especially with fish that like to perch like hawkfish or gobies.