If you're not a Premium member, you may have noticed that when you analyse your games you sometimes see a prompt to upgrade to premium. That's because basic analysis and the full analysis available to premium members are a bit different!
So, what's the difference?
Basic analysis will allow you to see all the 'best moves' and 'blunders' in the analysis tab, as well as view lines and see variations just like in full analysis. However, the analysis is done at half depth. this means the computer only looks half as many moves ahead to determine the best moves.
Premium analysis will allow you to:
View your overall accuracy score (accuracy is shown as a '?' in basic)
Get deeper analysis insights (twice as deep analysis)
Get training recommendations (Puzzles and lessons suggested based on your individual game)
These above features are only available in the full analysis with premium.
However, as you may have already noticed, basic accounts do get full analysis once per day, so you can always see what the premium analysis is like and decide if you want to upgrade :)