If you aren't already a really good writer, Gammarly Plus will make your work worse because you'll accept everything it tells you, and most of its corrections (compared to regular Grammarly) are straight-up wrong. It ignores your voice, your audience, your tone, your context, etc.
That said, my work pays for Grammarly Plus & I put work-related blog posts (which will end up public anyway) through it. I like the plus version because:
It forces me to really reread everything, because it highlights fucking everything. Often I will make changes unrelated to what it's saying.
It often highlights things that can be improved, but not in the way it suggests.
Sometimes, it's actually correct.
But usually it's wrong. For example:
It tells you to remove passive voice 100% of the time. This is straight-up incorrect. For example, if you're writing a post in which you talk about a new feature or patchnotes, you will use passive voice all the time. Sometimes the object of the sentence is actually the most important thing.
It often says "be more confident!" and then removes any nuance in your writing that you were using to soften the blow of something, or to make something sound more exciting, or etc.
It always tells you things like "don't use the word interesting! don't use this other word! they are too common!" Well...
Using random fancy words is an anti-pattern. Keep on saying "interesting"
Sometimes, this word in question is LITERALLY A TECHNICAL TERM IN YOUR FIELD. STOP TELLING ME NOT TO REPEAT IT.
It always wants me to say "So," at the start of every sentence. Jesus shut up. This is a thing I'm trying to REMOVE from my writing because it's a bad habit.
Anyway. I'd say it's right about 10% of the time, max. Would I pay for it? Hell fucking no. Am I using it since it's already available? Yes, absolutely. But I'm not accepting many of its changes.
Again, though, REGULAR Grammarly is usually right. Unless you have code snippets HAHAHAHAHAHAHA have fun having your Python code proofread for the rule "comma goes inside the quote." lmao. Literally they could ignore everything inside triple backticks, but do they? No.
I use ChatGPT (Bing Chat) to rewrite my crappy English. I can ask ChatGPT to change the style, the tone, and length, wordings etc until I get exactly the results I want.
If you have Microsoft Word, just use the built in spell and grammer check. It's far more capable these days and is very feature rich.
Another user pointed out how much worse you can make your writing using it. I had a peer in a group project put our work through Grammerly and mindlessly accept what it said to do and it ruined the writing.
Mind you, I've never been a fan of Grammerly and certainly don't understand how people could pay for it. And certainly would never be comfortable using it for free, because then they're data mining me.
I used it throughout undergrad and grad school. I found it helpful. Not sure what you need Grammarly for but if you need MLA or APA help, I would recommend checking out Perra - www.perrla.com. Made formatting and references so much easier.
I strongly recommend deepl.com
It's by far the best among the ones I tried. It can translate using the appropriate wording for the context and it also has a section (deepl write, accessible from the topbar) where you can past your english texts and get better wording.
Also the free plan covers most use cases. If you need the pro it's worth it imo