It was confusing marketing. I didn't know what it was until I actually went through with trying it, and even then the game license ownership was unclear to me. It was weird how you'd buy a game upfront at regular price then not pay for streaming it later, UNLESS you paid monthly for Stadia Pro for the ability to stream at higher quality, which also came with some free games and hardware (?), AND there was a free trial version of it (which evidently deleted your free games when it expired).

I assume at this point that the license for the one game I bought was only good for Stadia, and I'm being refunded for it. That's good, cause Far Cry 5 got boring fast.