Last year, we had switched Dgraph license to AGPLv3.0, considering reasons like the ability to monetize in a competitive environment. In particular,
The threat of duplicate commercial services and enterprise features built by others without paying anything back towards the development of the open source version.
Update (Nov 2018): This post is outdated. Dgraph core is back to Apache 2.0, with no restrictions.
This remains a credible threat; nothing has changed in that regard.