I did a word limit for all 3 (Basic, Standard, Premium) but I charge more. 1000 words and under is $10 (I think). 1001–2000 is $20, and 2001–3000 is $30. But don't quote me on that.

It isn't just Grammarly. It's proofreading to make sure what's written is understandable. That the image fits the content. That the image has a citation. That if you're quoting a person or institution, credit is given. Ensuring that references are listed and that canonical links are working. Ensuring the writer doesn't tag 5M Medium users, etc. If there are affiliate links, it's stated so and clearly.

Basically, it's making sure the writer is Medium compliant.