royal court vip

How does the cumulative system work? If I charge/spend 1.5k on December, the unclaimed points will be brought forward to January or do I have to claim the reward else it will be reset counting from 0 again from 1st Jan 2015? I'd assume there is no expiry for the point system, which means whatever amount of rps charged will be calculated normally.

My understanding, please cmiiw.
1) charge 2k rps, spent 2k rps (December)
2) claim the bronze reward December (1500 rps lowest tier)
3) 01/01/15, 500 remaining will be brought forward, which means if I were to spend another 1k rps, I will be able to claim bronze reward again on month Jan.