Hello. I have problem with known words. I can’t mark words as known anymore, LingQ says I have reached my limit of 20 LingQs (because I am having free account), but I haven’t. I have 0 LingQs, and it says I reached 20. I don’t want to make LingQs, just wanna mark words as known. What should I do? Thank you.
If you created 20 LingQs but then deleted them you will still be at the limit. I believe you can get more LingQs by inviting friends to join LingQ.
I second Kimo’s suggestion of trying out premium if you can afford it. When I first upgraded to premium I decided I would just try it out for the summer… then I never switched back. If you do try it for a month, I suggest creating as many LingQs as you want and make sure you try out the importing feature. If you decide to switch back, I believe you’ll get to keep your LingQs but you’ll have to delete imported lessons so you have 3 or less (I think).
Thank you both. 
I had tried to press ‘‘K’’ and the word marked blue became known. I didn’t know I can mark the word as known by pressing the ‘‘K’’ button. Thank you once again.
Yes, I am planning to upgrade my account but I can’t afford to do it now. But in near future I should, I want to really make progress in learning the language that I am learning on LingQ.