Hello I am currently looking for a Max Res Voucher. If you have one please PM me and we can discuss the price. Thanks! Wiki: https://empireminecraft.com/wiki/max-res-upgrade/
It gives you an extra res with a max of 6 total. You can't get them anymore so they are very expensive.
A diamond voucher can provide a player with what is called 4 "temp" reses. However these vouchers adds a "permanent" residence to your total. Diamond Voucher = 4/1 (4 temps with 1 permanent) Max res voucher with diamond voucher = 4/2 (4 temps with 2 permanent) You can get a max of 4 temps (Achievable with a diamond voucher) and 2 EXTRA permanents (achievable with 2 max res vouchers).
Meaning that once the voucher expires if you unclaim it you will not be able to claim it again unless you get another voucher.