Unfortunately we receive a tremendous amount of abusive and fraudulent signups which is why we require customers to unlock their accounts and activate their promo code at the same time.
We currently use BrainTree Payment Solutions as our credit card processor and they are fully PCI complaint and store your credit card data. We do not store it ourselves. We are also looking to potentially switch to Stripe as our processor.
Outside of that you can also send a one-time payment using Paypal and not save your credit card if you are worried.