The instructions are given for two codes, but I find no information to apply the third. In fact, looking at the UI it doesn't appear that there is any limitation for two code users (maybe the third is not required?)

Please confirm this information provided in a previous answer and (if applicable) explain the process to apply a third code:

Quotation of your answer:
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> For AppSumo users:

1 code: General interviews (Starter equivalent)
2 codes: Some specialized interview types
3 codes: Full Professional access with all interview plans

The key difference is personalization - Starter gives you generic practice, while Professional creates tailored interviews based on your specific role, experience level, and target companies