How to stop trading after reaching target?

Hello,
I would like to have my EA stop trading after it has reached a target in a pre-defined period of time.
For example, I would like the EA to stop trading after making 20 pips a day (or week, or month), or a certain amount of money (set by user or set by percentage of account balance at start of trading period) as defined by AccountBalance() in a day (or week, or month).
I don't know what command to use to order an EA or script to deinitialize and not take any more trades for the rest of the period. If anyone knows, please let me know how its done.

Thanks,
Ravi Desai

store the accountbalance in a global variable at the beginning of each time period and when the balance exceeds the predefined amount you stop trading. Then at the beginning of each time period you copy the current account balance to the same global variable.

global variables are stored permanently (provided they are accessed at least once every 21 days). Even when mt4 has been exited.