We use the 'limit renewal to within X months/days' for 2 purposes:
1. allow early renewals, 2 months before the annual expiry date of 1 Jan
2. allow renewals up until membership benefits lapse, 3 months after expiry date (i.e. members lapse automatically at 31 Mar

We need two limit fields to handle this, not just 1! As it is, we need to go in and change this field from 3 to 2 months on 31 Mar for all of our 20+ levels.

Moreover, within the early renewal period, existing members who change levels should be treated as renewals, not as new members (i.e. their renewal date does not currently update update correctly if they change levels as they are charged for the current year as well as requiring payment for the renewal year!)