Market question???

I've been reading the Market Forecast. They constantly refer to the lows or highs from previous months.

How far back is resistance and support valid? When were talking about Support from July for say Eur or Gbp. If anyone was long from the July lows shouldnt they have already shaken out of the market at say the Sept highs? Who provides that support?

Resistance and support validity depends on your trading style. If you are a day trader, they would lose relevance quicker; if you keep positions open for longer periods of time, then highs/lows from three months back may still be valid