No No No. For a start modules have methods to do stuff: ie $lwp->cookie_jar->extract_cookies($response) However LWP takes care of this for you. *All you need to do is setup the cookie jar as shown*. The cookies you are sent will automatically be included in the header sent by LWP as appropriate. Note that in LWP the cookie_jar() method is actually just a reference to an HTTP::Cookies object so you can call any HTTP::Cookies method on $lwp->cookie_jar. Although you don't generally need to do it WWW::Mechanize is a subclass of LWP::UserAgent so (more or less) anything you can do with an LWP object (in terms of calling methods) you can do with your Mech object (unless that method got overridden).

If you are "stopping and starting" your program you can avoid logging in every time you run the program by saving the cookie to disk. See the docs, read them, and understand them.