I have a Lifetime subscription.

I also bought the lifetime sub when they were offering a discount.

I also bought the lifetime sub

Same, lifetime subscription to both ToneGym and SoundGym, though these days I am a bit disappointed by how ToneGym feels a bit abandoned by its makers.

after a few annual plans (and playing every day), I purchased the lifetime plan and stopped playing for 8 months 😅
But I'm back

Hello friend! I went straight for the lifetime after about a year of the free trial. That one year made noticeable differences in my production, so buying lifetime access was like a commitment statement to keep pursuing this! Enjoy your year subscription, everything happens in perfect flow ^_^

So I've been doing this fairly regularly for about 18 months to two years and I have to admit I get a distinct impression that the games do actually get a bit more difficult as you go along. Having said that, I think the training is excellent because the further you progress, the more instinctive it becomes. Sometimes you have to sit there and really work it out, but other times you know automatically what the answer is, even after a couple of seconds. Guess that bodes well for the future.