Change Default Estimate Expiration Date

functions.php

<?php // don't include this line in your functions.php, since it already starts with it.

function _change_si_default_expiration_for_estimates( $days = 30 ) {
	return 120; // change to the number of days for new expiration
}
add_filter( 'si_default_expiration_in_days', '_change_si_default_expiration_for_estimates' );