Sadly, you have to buy it but the prices tend to change since its a Japanese Import (costs 5,400 Yen plus Japanese Sales Tax). You can try it out for a month (31 Days) but for the most part, keep an eye on the currency exchanges.
It depends on which person/website you download it from. If you download the cracked version it won't work for you sometimes. If you buy it or download a clean, good cracked version, it'll be all fine.