Regarding the recent change in payout and people asking how much is to be paid, the OP states clearly:
You agree you will be paid the current rates offered at time of payout.
So I'd expect the new payouts even if your month started 29 days before the 0.4 → 0.3 change.
Re: the monthly spamming to renew, I think this is to reward active accounts only. If you stop participating in the forum, you won't get any reward from this thread, which looks reasonable to me.