You can download and try the software for free for 30 days.
After this period of thirtee days, if the software fits your needs and you want to continue to use it, you will have to buy a license.
Without a license, the software won't run anymore.
See the complete license text : Hearing Test Base - Licence - English.html
For the price of the licence, go to the page : Price of a license (link to the web site).
To buy a licence, go to the page : To buy a license (link to the web site).