The Expert Advisor requires that MetaTrader be running in order to function, MetaTrader 4 needs the computer to be working properly in order to function. So, if the computer crashes or there is reboot, power outage or any other type of interruption the EA will not work. There are two scenarios from this point on. 

1. There was no trades opened when MT4 was shut down.
2. There was at least one open position when MT4 was shut down.

There was no trades opened when MT4 was shut down. - In this case the only impact would be missing an opportunity to enter the market. 

There was at least one open position when MT4 was shut down. - In this case the trade would have been opened with a StopLoss and TakeProfit levels that would remain valid even after the (EA/MT4/computer) was shut off. However, since the EA is the one that manages the TrailingStop and that is the most common way for the profitable trades to exit the market given the high TakeProfit level, the trade would more than likely get stopped out if MT4 is not back on line before the trade is closed. If there is a computer reboot while a trade is open, simply start MT-4 after the system is back online and as long as the EA was not removed from the chart, the EA will pick up right where it left off. It will recognize its open trade and continue to manage it as usual.

Turning the robot on and off

If for any reason you need to turn off the GBPBOT you can do so by clicking the "Expert Advisors" button on the top toolbar:

When this button has a white background, it means that Expert Advisors are active and able to open, close or modify trades.