I think the issue here is that most people (including you) tend to go with the 'bare minimum' when it comes to lighting. Unfortunately, nems REQUIRE good light. I dont even agree with T5, I think halide is what is needed. Most people buy a nem and do the lights as an afterthought. YOU MUST have adequate lights to sustain the life of this animal. by giving it less than what it needs you are torturing it. And dont just go off of what one or a few people say "well I have these lights, and my anemone is still alive" thats unusual, and we really dont know how healthy their anemone is.. especially long term!
Take the nem back or get the money and buy the adequate equipment. No one said this hobby was cheap, but it can be if you only do certain things. Getting an anemone is not one of those things.
Sorry, but you need to take it back.
Jess