Of course, for speech recognition to work on an end user's PC the system must have a speech recognition engine installed on it. The application has two choices:
The application can come bundled with a speech recognition engine and install it itself. This guarantees that speech recognition will be installed and also guarantees a certain level of quality from the speech recognizer. However, if an application does this, royalties will need to be paid to the engine vendor.
Alternatively, an application can assume that the speech recognition engine is already on the PC or that the user will purchase one if they wish to use speech recognition. The user may already have speech recognition because many PCs and sound cards will come bundled with an engine. Alternatively, the user may have purchased another application that included an engine. If the user has no speech recognition engine installed then the application can tell the user that they need to purchase a speech recognition engine and install it; Several engine vendors offer retail versions of their engines.