Automatically Add Tags Taxonomy in Post from Custom field's value

Hi,

I want to automatically add my custom fields value as a tags when i publish/save the post.

First Tag:

My Custom field’s id is: app_name

I want to add "Download Free app_name Latest Version" as a tags automatically after publishing the post.

Second Tag:

My Custom field’s id is: app_dev

I want to add "Get app_name By app_dev from Here" as a tags automatically after publishing the post.