It is impossible to discuss this software version without addressing the prevalence of "cracks" or "keygens" found online. Because version 6.4 is old, legitimate activation servers are often unresponsive.
Genuine activation requires a license key purchased from IVT. Historically, many users received "pre-activated" versions bundled with specific Bluetooth USB dongles, where the license was tied to the hardware itself. Bluesoleil 6.4.249.0 Free Download And Activation