Not with Tappla today, and we'd rather say so before you sign up than after. There are two reasons.
Viewers can't buy inside the apps
Tappla does not collect payments, and your apps have no purchase button. Buying inside a TV or phone app has to run through the store's own billing (Apple, Amazon, Google, or Roku Pay), and Tappla does not offer that.
The live stream can't be locked
Members-only works on playlists. The live stream in your apps is always open to every viewer.
What does work: recordings for paying viewers
After the event, add the recording to a playlist and mark it Members only. Sell access on your own website, and have your checkout email an access code. The viewer enters it once per TV. This works on Apple TV, Fire TV and Android TV, but not on Roku. See Members-only content.
If in-app pay-per-view is what you need
A platform built around paid video, such as Uscreen, sells inside its own TV apps. It will serve you better than we would.