AEC membership is intended to renew automatically roughly every 30 days from the day you join unless cancelled. If after a 30 day period you find you no longer have access to the AEC side of the daily login streak ladder, there has likely been a problem renewing payment. Payment failures can come from a number of things: using a $50 prepaid card for AEC signup, insufficient funds, or card issues on the side of your bank, for instance. You can easily check your payment status by logging into our webapp and checking your payment info via the link on the AEC page.
Don't worry too much; your login streak will not reset to Day 1 and you will be able to continue to collect from the free side of the ladder until the payment failure is resolved, as long as you keep logging in daily. So, if you were on day 30 and then experienced a payment failure, you will still be able to collect a reward on day 31—it's just that you will have to do so from the free side of the ladder. Once the payment failure is resolved, you'll jump back to the AEC side of the ladder from the day of resolution onward for as long as you remain a member. The next 30 days of AEC will start from when the payment failure is resolved.