Way to mark words unknown without making a Lingq?
At the moment that's not possible, unless you avoid to complete a lesson. That way blue words will remain blue (you also need to disable "Paging moves to known" in Settings).
Why not just pay for a month and use it to your heart's content? A month is not a large investment - it's much better to examine the product fully, particularly if you're planning to recommend it to friends. You'll end up paying far less than $20 dollars - less than a dollar a day for the privilege - and by the end of the month you'll know whether it's a product for you and you'll know the full extent of the pros and cons when recommending it to friends :-)
I have a pro account :) And the people I'm concerned about recommending it to are my adult students not my friends :) Actually I would like to send them articles through LingQ but seems quite rude as a teacher if they hit a paywall before finishing the first article :)
Also, as an advanced learner, you don't want to immediately memorize every word you see! This is my real concern :)
I'd say it's a bit wrong mental model here. Blue words don't mean _unknown_ they mean _not seen before_. Your 1s are just to show you that you've seen the word before. Why would you avoid it? It's kind of a mark to help you to remember the word in the future, not really to memorize.
Trial is pretty useless indeed though.