Yes, of course. That is a major reason why people use open source. And since AWS was a contributor to Redis, why it would be absurd for them to pay license fees on a project they helped build and maintain.
It'd take a lot to get developer adoption and buy in to a separate product that AWS builds themselves, so they adopted Redis. Easy money. It's easier to piggyback on something that won while making lots of money from it and say "well, I helped..." if things chanbge. Then, they chastise the creators as bad people once the gravy train stops.
AWS benefited from hosted redis before contributing. It wasn't adopted out of benevolence. They're still doing it with Memcached, for what its worth.
Redid Labs did not create Redis. They were the original leeches in this, in a way, from my understanding. They just bought the trademark from the dude who actually did create it.
Someone else made more money on the property they were trying to appropriate from the community, so they decided to add an artificial barrier to competition and found out what happens when the other players are bigger than them.
Redis Inc also wanted to sell managed Redis, but they can't compete on price/features with AWS, so they instead used the leverage they bought over the Redis community to make Redis effectively non-FOSS.
AWS doesn't depend on Redis. They only have a Redis managed offering because people keep asking for managed Redis. They were also actively contributing to Redis. They really did everything right here, but it still wasn't enough for Redis Inc.
Note that I am not affiliated with either AWS or Redis in any way. I don't even use it in any of the projects I work on. I've just been following this conflict because I am interested in the way open source communities work.