Could you please explain the process of purchasing API3 in a step-by-step manner? Are there any specific platforms or exchanges that support the trading of API3 tokens? What are the potential risks and considerations one should keep in mind before investing in API3? Additionally, is there a minimum investment amount required, and what are the associated fees for purchasing and storing API3 tokens? Lastly, are there any regulatory considerations or restrictions that investors should be aware of when buying API3?