My friend told me that on the relaxer labels it says to throw out left over relaxer. I told her I was going to buy a big container of relaxer and she wanted to know why, since you have to throw it out. She said it says "For Professional Use" because a hairdresser will use a large container within a week on their client's hair, but if we buy it, then it will sit for about 2-3 months until we use it again for touch-ups. This is the first time I have ever heard this. Has anybody else heard about this? So, how long does a large container of relaxer last? Is it still good if I use it 2-3 months later? I'm trying to determine if it is worth buying a large container of relaxer. Any expressions will be welcome.