The primary source for the is the Siemens Support portal. Siemens typically offers the software as a "Trial" version which is fully functional for 21 days.
Log in to the portal. Navigate to the "Download" area and search for "SIMATIC STEP 7 PLCSIM V15.1". You will need to select the correct DVD image (ISO format). plcsim v15.1 download
To download PLCSIM V15.1, follow these steps: The primary source for the is the Siemens Support portal
During the installation, the setup will ask for a license key. follow these steps: During the installation