From reading this link :
I understand that the free license "is designed for personal" use and you can "index up to 500MB/day".
2 questions :
1) Do you breach the free license if you have 3 independent Splunk servers on free licenses indexing 300MB a day (total 900 MB) ?
2) Do you breach the free license if you use it in a corporate situation ?
1) No. Multiple separate instances are fine.
2) No. The free version lacks features that are often useful in a corporate environment.