Email me directly. I read every message and I answer them myself.
Two things cause this. Give it a few seconds first, since iOS applies the block with a short delay. If it still opens after that, go back into Merit, tap the app picker, and select your apps again. iOS occasionally rotates the internal tokens that identify your selections, and when that happens the old ones stop matching anything. Re-picking fixes it. There is no warning when it happens, which is a limitation of the Screen Time API rather than something Merit can detect for you.
Merit settles your balance when you open the app, and it recalculates the whole day rather than adding increments, so late-arriving data from a watch gets picked up on the next settlement. If nothing shows up at all, open the Health app, go to Sharing, and check that Merit still has read access to steps.
Use the allowlist. Anything on it stays reachable while everything else stays blocked, and you can edit it however you like. This is free and always will be.
Tap Restore Purchases in settings. The unlock is tied to your Apple Account, not to the install, and it is a one-time purchase, so there is nothing to renew or resubscribe to.
There is nothing to cancel. Merit does not have a subscription. If you bought the unlock, you own it.
Email me. Tell me your iOS version and what you were doing when it broke. Screenshots help. I would rather hear about it than have you leave a one-star review and move on, although you are of course entitled to do both.