When you first purchased your futon included was a small hex wrench that was used to tighten your futon frame. This handy little tool went around and tightened the 8 bolts in the arms of your futon that connect the stretchers and once you were finished you had a great looking assembled futon frame. If yiu have decided that your need for the hex wrench was done and decided to toss it away.
This was probably not a good thing. As futons are used the bolts in the arms gradually loosen over time and as they continue to loosen the weight of the mattress and people everyday can put un-needed stress on those bolts at the connecting points. If these bolts are left un-tightened gradually they will start to bend from having become loose and one day you may be looking at a stretcher rail on the ground that has had bolts bend out of it from the rail loosing up against the arms. This is a very sad thing when this happens and much like putting oil in your car to prevent engine damage this too could have been prevented.
The allen wrench should be brought out every 6 months to a year and used to tighten up the bolts on the outside of the arms. Doing this will keep the connection tight and will help reduce wear. Another thing to do is look at the pins that connect the seat and back section together as well as the pins that connect the nylon rollers. Make sure the little cotter clips are still attached through these and if they aren't put them back in or purchase replacements to make sure these pins don't work loose. Just a little maintenance for your futon a couple of times a year will keep it in great condition.