The $50 subscription is to avoid flooding their servers while testing the software.
This product will likely starts as a corporate malware but once the beta is over and their tech is really working at scale (more difficult than you might think) they'll probably give it for free or very cheap.
They wont give away this for free:
> Each browser instance gets 16 vCPUs using state-of-the-art Intel CPUs running at up to 4.0 GHz.
People would mine bitcoins with it. Not to mention they'd be footing more than all of youtubes bandwidth costs if this gets popular.
So you think it is a dragnet-surveillance get-acquired-for-our-data play, longer term? That's even worse, if so.