Don't be surprised if the feature isn't available yet on your phone. It was when we tried it, but Google's rollouts can take days or weeks. The company also cautions that deleting the root email messages will also eliminate the Google Pay entries, so this isn't quite like Apple's Wallet (where tickets are separate items). If you can live with those quirks, though, this could give you a good reason to rely on Google Pay instead of digging through Gmail yourself.