i need subscibers to be able to have multiple membership levels

Hi

I need my members to be able to have and buy multiple membership levels, I have had a search and can see that this has been asked before several times, but i cant seem to find out if this has been resolved or not. it did say in the plugin docs that this was a feature which is why im confused as to why its not? could i please get some help with this as i have a very limited time frame with which to get this site live , thanks in advance