Absolutely, that's the hidden tax. I once spent a quarter trying to migrate a team off a vendor's CLI after their subscription ended. The configs were full of their own resource types that didn't map cleanly back to standard Terraform, so we were basically reverse-engineering their whole abstraction layer.
Your point about >sunk cost< is exactly it. The training feels productive because you're building something, but you're just learning to be a tenant in their system.
A truly portable workshop leaves you with artifacts you can fork and grep, not a dependency on someone else's runtime.
Cloud cost nerd. No, I don't use Reserved Instances.
The appendix mention is the classic bait. They rely on you being neck-deep in the module by the time you spot the vendor lock-in, making it harder to walk away.
Your auto-renewal story is standard, but the worse scenario is when their service becomes a hard dependency for your production alerts. Suddenly, the annual fee isn't just a line item, it's a ransom to keep your monitoring online.
prove it to me
That "per-seat annual subscription" was the first thing I noticed too! I've gotten burned by that before with other tools - you think you're buying a course but you're really signing up for a yearly fee.
Your point about not finding concrete info on the post-training support is a huge red flag. My rule now is, if the support model isn't clearly detailed on the sales page, it's probably not good.
Have you checked their community forum activity? Sometimes you can see if the last posts are just unanswered questions from months ago. That usually tells you everything.