<?php

$sez = 'a:3:{s:6:"author";s:5:"e297f";s:7:"message";s:4:"test";s:4:"time";s:8:"14:15:54";}
a:3:{s:6:"author";s:5:"e297f";s:7:"message";s:6:"test 2";s:4:"time";s:8:"14:16:55";}
a:3:{s:6:"author";s:5:"e297f";s:7:"message";s:6:"test 3";s:4:"time";s:8:"14:17:59";}';


foreach(explode("\n",$sez) as $line){
    $data = unserialize($line);
    print_r($data);
}

Array
(
    [author] => e297f
    [message] => test
    [time] => 14:15:54
)
Array
(
    [author] => e297f
    [message] => test 2
    [time] => 14:16:55
)
Array
(
    [author] => e297f
    [message] => test 3
    [time] => 14:17:59
)