Is it only ever going to be created_by and updated_by? What happens if multiple users update the package, you only want to track the person who updated it last?

If so, then your design can just be this without the need for a pivot table:

Customers
-----------
id
name

Packages
-----------
id
name
created_by (customer_id)
updated_by (customer_id)

However, if you'd like to track all users that update a package, you could do something like this:

Customers
-----------
id
name

Packages
-----------
id
name
created_by (customer_id)

Pivot (tracking updates)
-----------
customer_id (primary key)
package_id (primary key)
updated_at (timestamp)