What license is elk stack?

Excuse me, could you clarify what you mean by "elk stack"? I'm not familiar with this exact term in the context of cryptocurrency or finance. Perhaps you're referring to a technology stack that involves Elasticsearch, Logstash, and Kibana, often referred to as the ELK Stack? However, this is a popular logging and monitoring toolset used in software development and IT operations, rather than being directly related to cryptocurrency or finance. If my assumption is incorrect, and you're asking about a specific license related to cryptocurrency or finance, could you please provide more context or clarify the terminology you're using? It would help me to give you a more accurate answer.