Samsung did begin preinstalling Samsung Pay all the way back from 2015. But it was done only in the USA and South Korea, and only on the exclusive flagship devices. Now, that is changing as Samsung is aiming to preload the service on less costly devices.
Samsung Pay Mini is also launching next month. This will be a different version of the Samsung Pay app which will be compatible with non-Samsung phones. Apple however, rejected this proposal.
If everything goes according to plan, Samsung expects to expand the Samsung Pay service in Russia, Malaysia and Thailand before the end of 2017.
If you have a compatible Samsung smartphone you can try out the service right now. Just download the app from Google Play Store!