I kept running into the same problem while building SaaS products: free trials are supposed to make it easy for real users to try the product, but some people are very good at abusing them. One person can create multiple accounts using different emails, VPNs, proxies, disposable devices, or combinations of different signals and keep getting the same trial over and over. I initially tried solving it with simple things like IP limits and email checks, but they were relatively easy to bypass an...