IMO 6 months is the least amount of time needed to house anemones. That is assumming you have done your homework on their care.
A novice anemone keeper should have at least a 50 gallon tank or larger. The larger the tank the more room for error you will have.
Feeding is necessary for anemone health. You can keep an anemone alive on light alone,but it will not be a content and overall healthy anemone. Most clowns bring food back to their anemone,but it is often to protect it's catch from other fish and not to feed the anemone. However,anemones eat the feces of the clowns. Which is utilized by the anemones zooxanthellae. So light is not really enough to keep an anemone at optimal health.
I feed my anemones directly with silversides and krill(I have bubbletips and a H.crispa)and others also feed squid,worms,shrimp,and fish filets.
It is a comonly accepted theory that anemones need high intensity lighting(Metal halide,VHO,PC). Feeding IMO is more necessary,but lighting is a great backup. I feel they are both necessary for optimal health.
It is also true that anemones are mobile,and they will move where THEY think is best. The problem with this is that the anemone sometimes ends up on your heater,powerhead,or overflow. It is necessary to cover or hide these items. They like a moderate to high flow and additions of iodine and trace elements.
Let us know what hardware you have and we will help you.