Payment for app across multiple platforms?

I have bought the Channels app from the google play store (for primary use on my Nvidia Shields, and also from the apple store. I have also subscribed to the DVR service.

I am now opting for FireTV Sticks for other TV’s in my house - do I need to buy the app yet again for that platform?

Thanks

Yes, the various App Stores offer no ability for cross purchase.

Would the use of Promo codes help with this. I underhand that the Google Play store has recently updated to allow for them.

The app store can do promo codes as well…

Only thing is not 100% about the firetv store… but amazon should have it

So a user would purchase the app(s) [hopefully with a discount when multiple are selected] and appropriate (one time) Promo codes will be generated for each app that the use can then use to install…

Amazon does not provide promo codes. Apple/Google explicitly prohibit selling promo codes in anyway. They want all transactions to go through their store, so that they can take their 30% cut. There is also a hard limit on the number of promo codes you can generate.

It seems unfortunate. Oh well, I am now invested in Channels to the tune of $65 (3 app store purchases!) plus the $8 monthly fee. At least I can download the apps onto multiple devices I use!