Apache-2.0-licensed. Use it.

The Apache License 2.0 permits broad use, modification, and distribution — including commercial use — when the license and NOTICE files are retained and changes are stated. It also includes an express patent grant from contributors. The canonical text lives in the repository root LICENSE file.

Read the LICENSE file Source on GitHub

What you can do

Use, modify and redistribute it, including commercially, under the Apache-2.0 terms above.
Embed the engine in your own products and services.
Everything in the engine repository is open source: nothing is gated behind a paid tier, and the engine sends no telemetry.
SR Cloud, the hosted product in early access, is separate and optional.

Support & security

Bugs & questions → GitHub Issues and SUPPORT.md.
Contributions → see CONTRIBUTING.md and CODE_OF_CONDUCT.md.
Security reports → private reporting, as SECURITY.md describes.