most people with bamboo in planters or contained areas will divide or root prune every few years to keep the plant from choking itself out. in addition it is nice to replace the dirt from the rootballs you removed with your own topsoil mix. without maintenance it will become just like the 1 gallon plant you've seen sitting at the nursery for the last 5 years, rootbound. if the planter is too small for the boo to become mature, then you'll have a dwarfed plant.

find some friends to give a bamboo start or specimen to. if you'd rather not do the work you can put an ad online and someone will usually be glad to remove some for you in exchange for the removed bamboo itself.

Yes, it will eventually choke itself out if you do not divide it. That happened to one of my runners this year, and I knew I needed to divide it but kept putting it off.