This command is off by default. If turned off, you will not need to identify for your nick to get access in rooms when you match your nick's access list. If the room has ident set on, then you will have to, even if you have secure set off.
Enables the 'enhanced security' mode for nicknames. When enabled, NickServ does not check access lists at all, and positive authentication via password is required before you can use your nickname. For information on how services will protect your nickname please see the nickserv PROTECT.
Example:
/msg nickserv set secure off
You should probably leave secure on. In general, it is best to always identify for your nick by password. However, if you have a static ip address, you might prefer the convenience of getting opped without identifying. Just be careful to make sure you don't forget your nick passwords because you are using them less often. If other people start getting op access because of your nick's access list, then you should set secure back on.