From what I understand, the free version will let you learn 50 new words a day and "review as many as you need". However on my Android app I'm unable to review any words after I've reach the 50 new word limit, even though I have words to practice. When I reach the limit I get a screen telling me I've reached the limit and giving me the option to subscribe or stay with free. When I select "stay with free" it sends me back to the progress page. At that point if I select "learn" it again gives me the screen telling me I've reached the limit. Then back to the progress page. Etc. So I can't use the app at all after I've reached the limit.
At lingvist.com I can continue to review words after reaching the limit, but after each card I get the screen telling me I've reach the limit. When I select "stay with free" I get another card - but after that card I get the limit screen again. I have to click though that screen after every word to continue reviewing.
Hope these can be fixed soon, especially the Android app. Love Lingvist by the way!