I've never heard of Claude. I've had success simply putting a paywall in front of a custom GPT bot url link. It's a one time payment for access to the link of course, but money is money. I had openai API integrated in initially to keep my prompt in house and confidential. I didn't like the token cap and how expensive it was so I reverted to the simpler option. Nobody cared. The vast majority of people in my network are not tech savvy at all. This has been my most recent project. Nothing huge, but it's a need in my niche.