You can easily add a free or premium (paid) product (questions set or course) to your library from the Shiken Store.
Head to the Shiken Store from the navigation bar
Premium (paid) products are identified by a price within a blue button on their product card
[Optional] You can use the filter and search buttons in the top right of the SHiken Store to filter by paid products or search by a product name
You can instantly purchase a premium product by clicking on the blue button
You will then be asked to choose the length and price of your subscription, if you have a discount code you can enter it here too.
After selecting the length of your subscription you will be taken to the stripe checkout page to securely complete your purchase via card or Apple Pay.