redpill accepts credit/debit card payments for redpill Spy and redpill Detective, but not for the more 'hard core' penetration testing software like redpill Hacker and redpill Agent. For those products redpill uses Perfect Money and Webmoney.
Some customers complained as Perfect Money and Webmoney is not supported in the United States and difficult or expensive to load from some countries. To help those customers, redpill now also allow bitcoin payments that is available everywhere including in the US.
To purchase using bitcoin, just select that option in the Purchase page of the redpill website.
For more info about bitcoin click here. To get started is very simple and quick. You can install a wallet app from https://bitcoin.org (tip: install a lightweight client and not a full node like Bitcoin Core as a full node needs to download tons of data).