All of this is available in your customer portal. You are 100% in your control of downloading a PDF or printing a copy of your invoice or receipt.
You log into the portal with the email you used to subscribe/sign-up. The customer portal is located here:
https://subscriptions.knownkeep.com/p/login/bIY5m2ent3aLgIEbII
Should you have any issues or questions, just open up a support ticket here in this forum.