How can i make an indicator expire?

How do you make an EA expire? What is the code that is needed or a website where i can see sample code?

Trial period protection:

If you want to give the user of the program a try-before-buy program you can limit the usage of your program by limited period of time and after this period the program will not work.
Use the code below to limit your program for period of time.

int start()
{
string expire_date = β€œ2006.31.06”; //<-- hard coded datetime
datetime e_d = StrToTime(expire_date);

if (CurTime() >= e_d)
{
Alert (β€œThe trial version has been expired!”);
return(0);
}
// your normal code!
return(0);
}