Hello,

in regards to updating your plugin, the most important step is to check this option;

In the main plugin settings/'Prevent deleting tables in database'.

When you have that enabled, it means that all your tables, settings and charts will remain safe in your WordPress Database, so you can safely update the plugin.

If you activated the purchase code in wpDataTables Settings/Activation, the update should be offered in the Plugins section. On some WordPress installations, you need to deactivate the plugin first in order to see the update offered, so please try that.

If that doesn't work, try going through Dashboard/Updates. 

See if you can update the plugin through there, and if that doesn't work either, you can follow the manual update procedures from this Guide :

Updating the plugin to the latest version

Let me know how it goes.

Thank you.