Yes it's OK to use Hamburger Helper after the expiration date.
The expiration date on Hamburger Helper is just a general guideline to let you know when the Hamburger Helper is no longer considered fresh.
But the Expiration date does not mean that the Hamburger Helper is bad and unsafe to eat.
As long as there are no bad smells to the Hamburger Helper then it's okay to eat it for many years past it's expiration date.
Overstock and food bargain stores are allowed to sell foods such as Hamburger Helper, Canned Goods etc well past their expiration date.
And they can do so legally because the food is actually still very safe to eat even years past it's expiration date.