LimeLM only auto-upgrades accounts when limelm.pkey.generate or limelm.pkey.setDetails web API with activation count that adds more to your total allowed activation count.
So, if you want to prevent this behavior either keep track of the number total activations and stop using the web API when that number is hit.
Or if youre doing tests and youre generating a bunch of keys make sure the person doing the test verified your account didnt change after all the tests.