Nothing will happen to your account in that case. Basically, that just means that we guarantee that you will notice significant progress in your study language if you meet your targets for 90 days.
Judging by this, it seems there was at one time a money-back guarantee, on the condition of actually meeting targets for 90 days?
@zoran if that guarantee still exists, I’d highly recommend making it clear - if it doesn’t, I’d highly recommend deleting that line. Currently, it’s lacking any context and, if anything, seems intimidating in connection with subscription fees.