Nginx Pro is a bit expensive. I haven't looked into their licensing, but usually with paid software, the biggest issue is activating licenses and stuff, which can't work nicely with autoscaling. One example is when wanted to buy the commercial version of s3fs back in the day - it required running some tool on your server and emailing the guy the hardware signature so that he can email you a key for that server. I'm not saying this is the case with Nginx, but in general, the more strict you make your licensing, the less revenue you're gonna collect. FOSS that charges you for extra features is pretty much doomed - nobody wants to use the less capable version and subconsciously or consciously starts looking for alternatives. Charging for support I truly accept - that's the way to go and it keeps the attitude positive.