Focus Mate. It's a service that pairs you with a "co-worker". You're both working on (your own) project, but you check in at the beginning of the hour-long session, and both of you say what you're planning on doing that session.

Then at the end of the session, you and your partner check in again, to tell how you did.

It's really useful, it gives some accountability to get going on projects, and get you unstuck. Also when I set up a session for 6.30 in the morning, I'll actually start work at 6.30 in the morning, and I sometimes need a nudge like that.

PPQ.AI It's not exactly subscription, but I use http://ppq.ai instead of ChatGPT. I'm happy with it. Anonymous, pay per query, just like it says, and also you pay with lightning. Lots of different models to choose from.