How can a software be encrypted with a hardware dongle?

How can a software be encrypted with a hardware dongle?

"Dongle" is a kind of encryption product which is a combination of software and hardware inserted in the parallel port of computer. Generally, there are dozens or hundreds of bytes of nonvolatile storage space for reading and writing, and now the newer dog also contains a single chip microcomputer. Software developers can exchange data with softdog through interface function (i.e. read and write softdog) to check whether softdog is inserted in parallel port, or directly encrypt their own EXE file (commonly known as "shell") with tools attached to softdog. In this way, software developers can set multiple software locks in the software, and use the softdog as the key to open these locks; if the softdog is not inserted or does not correspond, the software will not run normally

So the dog is relative to the software, can not encrypt technical files