Anemones, mostly, are impossible to keep for lenghts of time, I could look up the stats but its like 1 out of 35 or something people have had an anemone over 5 years, and those were experienced persons.
Typically it takes a few year old tank to host anenomes appropriatly, unless you have transfered from a longer lived aquarium some of their materials, filters, rocks, etc. . and still you need a very established tank, preferably with various algaes growing.
In other words, please do some anemone research find the hardy ones and the not so hardy and circumstances needed to keep these animals. They are normally brought from reefs and they typically reproduce very slowly and can live, I understand, hundereds and hundereds of years, but not so much in home aquaria and when they die they can foul a whole tank up killing everything, this of course depending on what anemones you plan to keep.
Just some info to take into consideration, hope it helps, and maybe someone with a long term experience with them can chime in?