With the AMBOSS membership, you will be able to answer 50 questions in one month. You can answer the same question multiple times, but each repeat will count toward your 50 question limit. Reviewing a previously answered question also counts toward this limit.
With an upgrade to unlimited questions, you can answer as many questions as you'd like, as many times as you like! Questions can be recycled into future question sessions and you can create folders with questions you would like extra practice on. Similarly, you can select an option in the custom session mode to exclude questions you have already answered.