Helix will accept any payment from a major credit card, such as Visa or Master Card. There should be no problems with processing your payment if you HSA or FSA card is provided by a major credit card company.
**Please note, HSAs are managed through your health benefits. At some point, your HSA may ask you for a receipt and a description of the product you purchased. It's up to the HSA to determine that App is a valid medical expense. You may want to contact them to verify this before placing your order.