What is a monthly limit?

Each month, you have a certain amount of gems that you can redeem.

This limit is set up by the company or person that runs your program and helps them plan how much to spend on the rewards offering. If you get a message that says you don't have enough gems for the reward you're trying to redeem for/claim, but your balance is more than the cost, you've likely reached your monthly limit. 

But don't worry—the limit resets each month, so you'll be able to redeem at the start of the next month.