Not saved in the table

You have an error in PHP. Put your code to file and debug it before blame the field. Assume that field works, it is easier.

As any other field also 42 should trigger an error if something is wrong, you should enable error reporting in joomla.

Thank you. 

Show code because I can not see the error.

What do I need to change that code to do what logic says.

Next time show your code like a text, we're too lazy to retype it from screenshot :)

As I see on this little screenshot you have a such string:

$sql = "UPDATE `#__cck_store_form_texto` SET fcont=".$fcont."where id=".$live.";

It's not correct, you haven't concat last qoute. Correct string have to be:

$sql = "UPDATE `#__cck_store_form_texto` SET fcont='".$fcont."' where id=".$live;

Really, you don't need to break qoutes. Double qoutes allow it:

$sql = "UPDATE `#__cck_store_form_texto` SET fcont='$fcont' where id=$live";

Good catch!
I would only add to this that everyone should be using Joomla query API (and not construct queries as strings), which mostly solves such problems by itself

https://docs.joomla.org/Inserting,_Updating_and_Removing_data_using_JDatabase

I tried to do as explained here.

See link

http://www.seblod.com/community/forums/fields-plug-ins/updating-an-acymailing-table-using-42-field