Answer:
The RF‑/STEEL Warping Torsion module extension is available in RFEM 5 and RSTAB 8.
To use this extension, you need the RF-/STEEL EC3 or RF-/STEEL AISC add-on module, as well as the corresponding license of the Warping Torsion module extension. If these requirements are met, the extension can be activated as shown in the following image.
More information about RF-/STEEL Warping Torsion can be found in the product description.