You have to buy a container about 3 to 6 inches larger in diameter than the pot you have. Buy whatever potting mix you are using currently and repot the plant. Before you do that, gently put your palm on top of the soil with the main stem between your thumb and forefinger. Turn the pot over very slowly over a towel or paper. Gently slip the pot off the plant when you have it upside down and examine the roots. If they are brown or black, wet or gooey, not good, repot immediately and do not water. Just be sure the mix you use for the new larger pot is moist when you use it. NOT wet.
If there are no rotting roots, but you can see them circling around the pot, especially on the bottom of the root ball, this means it is root bound. The only way around this is root pruning, which I do not recommend unless you are experienced, or the very simple fix, transplant it up into a larger container. It only have to be 3 or so inches larger in diameter to fix the problem. Then you check the roots again in about a month.
Best of luck to you. I'm sure it will be okay.