It's hard to say if it was worth the price. I purchased a lifetime subscription a while back at a discounted rate. I'm not sure if this a product that I would pay for monthly perpetually though.

Brain.fm does "work" in that it definitely has helped me focus, but I think one could craft a Spotify playlist manually with some effort in order to achieve a similar effect.

I think the key words here are "with some effort". Ultimately anything is potentially worth the price depending on the amount of effort a person is willing to dedicate to solving something vs having it "solved" for them.