i was told by adobe that you can use illustrator on both iPad and mac with one purchase

I was told that if i purchased adobe illustrator that i could use it on my ipad and desktop they keep sending me the same link over and over to check requirements but i do not see how one purchase lets you use it on both ipad and desktop it looks like you purchase it twice but then you have your work on two different devices instead of being able to work on the same illistration on both applications