Are you even allowed to store CC details of your customers on your servers?

I know that you are not forced to be PCI compliant by law, but if you are not and your database is leaked, you will be liable for any damages that result from that leak.

Anyways, I wouldn't ask for CC at signup because your business may come across as untrustworthy or a scam when asking for such data when the user is not buying anything at the moment.

Edit: Sorry my fault, somehow ignored the part of his message stating that he is using Stripe.