Limited # of characters in keywords field

Hi.

How much characters do you need? Length is limited by form element, not by storage. By default textfield has max length 128 characters, so this is the used value.
If you familiar (a little is enough) with module development for Drupal, as temporary solution you may implement hook_form_alter() (or more exact variant).

function mymodule_form_simplemeta_meta_form_alter(&$form, &$form_state, $form_id) {
  $form['keywords']['#maxlength'] = 255; // value you need... 255 is just example
}

Not sure is it really needed, but probably such settings will be configurable in next versions

#maxlength of title and keywords textfields is increased to 255 chars in 7.x-1.1. Should be enough.