They should concider a breakdown such as:
Renew any 1 premium option for-
1 wk: 3 nuggets
2 wk: 5 nuggets
3 wk: 8 nuggets
1 month: 10 nuggets.
Renew any 2 premium options -
1 wk: 7 nuggets
2 wk: 12 nuggets
3 wk: 16 nuggets
1month: 20 nuggets
Any 3 premium options -
1 wk: 10 nuggets
2 wk: 15 nuggets
3 wk: 19 nuggets
1 month: 24 nuggets
All 4 premium options -
1 wk: 15 nuggets
2 wk: 25 nuggets
3 wk: 35 nuggets
1 month: 40 nuggets
Doig this opens the option for those who only want one or two premium options and lets them concentrate on those...but at the same time allows others to take advantage of as many as they want..
By making it available on a decreasing overall cost by time period and options, you raise the likelihood more folks would invest in premium hence making more money overall. And by making it fit into a weekly and monthly purchase/redemption, you are better able to let the customer tailor his/her purchase to financial need.