You can use trainchinese for free, forever, and get enough training cards every week to sustain a basic learning program. If you're studying an intensive course like HSK, you may find yourself hitting the weekly or monthly limit, and in that case we'd invite you to subscribe for a small monthly fee to substantially increase these limits and enable you to store many more cards on this device, for browsing and learning at leisure. If you're a teacher, we have a special free subscription type for you too, permitting the creation of long word lists on the website that can be shared with your students.
However you use trainchinese, we wish you success in your Chinese studies!