1) How much does a license from 5gb per day cost?
2) Where could that be bought?
2) When license overcomes limit of 5gb per day what does Splunk happen? It stucks logging? It permits logging the same but reduced for certain days? Nothing, logging arrives also to 10gb?
you can find all the information you need about Splunk licensing at https://docs.splunk.com/Documentation/Splunk/8.0.5/Admin/HowSplunklicensingworks
Anyway Splunk continues to work but it messages to you that there's a license violation.
You can buy Splunk from you referral partner, if you're in Italy, contact me by private message.
About the cost of a license you can find some information at https://www.splunk.com/en_us/software/pricing/enterprise-and-cloud.html?utm_campaign=google_emea_tie...
to summarize. around 1800€/GB/year.