The most important thing on a widget is your data. However, it might be helpful to know when your data was updated.
There are two options to display this information, option number one:

Option number two:
You can add this information to your widgets that you have and I’m going to showing how you could do this configuration.

Go to My account >Visualization Preferences tab > Select the Widget footer option on the “Show last updated at” field.

Now your dashboards will be displayed the last update information on your dashboards.

This configuration will take less than one minute.
Please, left your comments below, see you!