I have string:
Verslo centrai Lietuvos nekilnojamojo turto plėtros asociacijos konkurse ...
Since your HTML is not properly formatted you could choose a preg_replace() approach:
$text = 'Verslo centrai Lietuvos nekilnojamojo turto plėtros asociacijos konkurse ...
';
$content = preg_replace('/<[^>]*>/', '', $text);
var_dump($content);
// string(108) "Verslo centrai Lietuvos nekilnojamojo turto plėtros asociacijos konkurse ... "
Codepad Example
On strip_tags() docs it says: Because strip_tags() does not actually validate the HTML, partial or broken tags can result in the removal of more text/data than expected.
Also second parameter is for $allowable_tags.