The error is telling you exactly what is wrong.
Call to undefined function SetPKeyDetails() in /Library/WebServer/Documents/test.php on line 111
SetPKeyDetails() is not in test.php, it's in LimeLM.php.
So instead of this:
$rtn = SetPKeyDetails($pkey_id, '1', 'btaber@gmail.com', 'users', '333');
It should be this:
$rtn = LimeLM::SetPKeyDetails($pkey_id, '1', 'btaber@gmail.com', 'users', '333');