Answer by lfx for Cookie is setting twice (duplicated)

Now you cookie stores for 60 sec.

time()+60*60*24*30 //this makes store it for 30 days.

from php.netexpire -

The time the cookie expires. This is a Unix timestamp so is in number of seconds since the epoch. In other words, you'll most likely set this with the time() function plus the number of seconds before you want it to expire. Or you might use mktime(). time()+60*60*24*30 will set the cookie to expire in 30 days. If set to 0, or omitted, the cookie will expire at the end of the session (when the browser closes)