Slight necromancy to also throw my 2p worth of support in for a non-subscription based alternative. With regards to being able to deploy new features whenever, rather than holding them back, how about this:
Have two tiers; the subscription, and a small one-time fee to buy access to the latest version at that time.
Let’s say you could pay something small like $5 and get access to v1.0.x, meaning any bugfixes would be included, but any features would bump the version number to v1.1 and require another payment of $5. New versions of PHP, even if it was just 8.1.6 to 8.1.7 etc, would count as a feature under this model.
The idea there being, we could pay for what we needed / wanted, rather than being forced to pay to keep an active subscription if we just need something basic.
If that would be too much hassle, then I would implore you to follow the JetBrains model and include a perpetual fallback license for the latest major version released at the time of your subscription lapsing. In other words, if we ended our sub when v1.1.0 was released, we’d get v1.1.x updates (bugfixes), but if you added any feature whatsoever, that would be v1.2 and we’d need to renew to get access to it.
This tool - while excellent - is only a convenience. I could knuckle down and spend a day figuring out a way to get all these old PHP versions into Homebrew itself - I used to have it, before I switched to Docker - and work out the SSL cert. This tool doesn’t do anything that would be next to impossible to replicate; phpStorm’s IntelliSense is lightyears beyond what you can replicate with VSCode plugins or Sublime Text plugins, and my time tracking software has multi-currency support which is useful as I bill people in different currencies.
I pay $7 a year to WoWHead to remove ads because it’s more convenient than constantly updating my adblock filters, and I pay $2.75 a month for Raidbots Premium because it’s more convenient to run bigger simulations for my WoW character.
My point is, if none of the subscription alternatives we’ve proposed will work for you, then please remember that convenience tools can only charge convenience prices, anything more than $3 a month (when paying yearly) is going to be a pass from me, sorry.