If you prefer the open-source fork, you can download Memtest86+ from Memtest.org .
Current versions of MemTest86 support UEFI only . For older machines with a legacy BIOS, you must download the Version 4 BIOS release. How to Create a Bootable MemTest86 USB
Visit the MemTest86 Download Page for the standard version by PassMark.
To ensure security and get the latest version, always download from the official sources:
Because MemTest86 runs before your operating system starts, you cannot simply "install" it like a normal app. You must create a bootable USB drive. Creating a MemTest86 boot disk in Windows