Aspen Plus 12.1 is a commercial software product, and as such, it requires a license to use. However, there are several ways to download Aspen Plus 12.1 for free, including:
These features are powerful, but they are worthless if your "free download" is a virus disguised as an installer. Aspen Plus 12.1 Free Download
Many universities have site licenses. Check if your school provides access via: Aspen Plus 12