Hey there everybody! 
I had set up more than 2 tiers of purchaseable ranks on my server, IE: supporter ($5), donator($10), patron($25) all of which have kits allocated to their ranks - my end goal is that you can only redeem perks from a single tier (preferably the highest one you own). I have seen this done on other servers, but i'd assume they featured modified version of this plugin. Would anybody be aware of how I could accomplish this, or at the very least I could impose a timed (IE: 24 hour cooldown) on the redeeming of any kit - that way they cannot purchase all the oxide ranks and potentially redeem 3 different kits?
Thank you!

You could possibly try granting the permission  for the first rank to supporter but revoke that permission once they attain the second rank which would then be granted the next permission, the third rank would have the second permission revoked when being granted the third permission,
The cooldown for kits is in the setup menu in chat,