You do need to pay for this. It's included free with TwinCAT 3.
This article provides a deep dive into what the Sistema library is, its legal and technical availability, how to access it legally at no cost, and how to integrate it into your TwinCAT 3 projects. beckhoff sistema library free
Absolutely. If you are a machine builder using Beckhoff TwinSAFE technology, using this library is not optional; it is the industry standard best practice. Failing to use it would be wasting billable hours on manual data entry that could be spent on logic design. You do need to pay for this
While the library file is free, using it requires a valid TwinCAT runtime license on your Beckhoff hardware (e.g., CX series, C6015). If you are using the Engineering environment (TwinCAT XAE) in "Config Mode" or "Free Run," no license is needed. For deployed machines, you must purchase a license from Beckhoff, but this is not a fee for the library. Absolutely