No you don't. PHPMailer contains two main php scripts: class.mailer.php and class.smtp.php. Copy these two files, along with the language folder that comes with PHPMailer to your webdirectory on the server.
Then when you want to send an email you will use code something like:
include("class.phpmailer.php");
PHP Code:
$mail = new PHPMailer();
$mail->From = "me@me.com";
$mail->FromName = "Me";
$mail->Host = "smtp.site.com";
$mail->Mailer = "smtp";
$mail->Subject = "Subject";
$mail->Body = "test email"; #HTML body
$mail->AltBody = "test email"; # Text body
$mail->AddAddress("abc@whatever.com", "John");
$mail->Send()
$mail->ClearAddresses();
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