GoPhone Data for iPhone6

Hi Together,

until now the shops, I have been, could not help me. 

I'm here (in he US) for 2 month and want to have data conection with my iPhone6 after I'll leave the office.

In this case I'm searching for a prepaid data card and I don't need text and speech.

Is it possible to use this card in my unlocked iPhone6?

http://www.att.com/att/gophone-tablet/en/index.html

The shop is trying to sell me the one for smartphones (45$ / 1GB / text & speech) but I want to use my mobile as a tablet.

What I understand:

- no annual contract

- prepaid with buying a new 30$ card after 30 days

- the card will deactivate 60 days after I didn't refill

So my question is: Will the just data card / plan work in my iPhone to use it as a tablet? 

Thanks in advance and sorry if I made many spelling errors (tourist)