You can only upgrade to Windows 10 using the same architecture -- for example, from Windows 7 32-bit to Windows 10 32-bit. In other words, you cannot do an in-place upgrade from 32-bit Windows to 64-bit Windows and maintain all your installed programs, plus a Windows 10 license.
It is, however, possible to 'upgrade' to Windows 10 64-bit if and only if you perform the in-place upgrade from Windows 7-32 bit to Windows 10 32-bit, first. Once that is done you will have your free Windows 10 license for the life of the machine. You can then reboot the computer and insert Windows 10 media and do a clean install of Windows 10 64-bit. That is the only way you can 'leap' from Windows 7 32-bit to Windows 10 64-bit, but you will have to reinstall all your programs and user files. As such, I recommend that you perform a disk image backup of your existing operating system before you perform the upgrade so that you can retrieve your files later, plus you can revert your operating system to the previous installation if you need to.