Download pages to my iPhone if I bought it from the Mac App Store?

I bought pages on my Mac a few months ago and I really wanted to have the app for my phone without paying for it again.

"I really wanted to have the app for my phone without paying for it again."
Me too. Won't happen. People in hell want ice water. You have to buy a different app. It's called "Pages for iOS".

Have you ever heard of Microsoft? They sell Office for Windows. Then if you have another electronic thing (computer) called a Mac, you have to buy Office for Mac. No freebies from them! Same with Apple. Two electronic things with different systems = two purchases.

I have bad news for you, they are separate apps, so you must buy the iOS version if you want it on iOS. Pages isn't the only app that have this type of pricing scheme, most 3rd party productivity apps are like this.

The good news is, you have the best version, which is the Mac version.