What happens if I do not hit the minimum spending for this month?

Your level will downgrade if you do not meet the minimum spending/points every month.

Example:
Jan: I earned 20 points and I reached level 2.
Feb: I earned 0 points and will be downgraded back to level 1 in March.
Mar: I earned 100 points and will immediately unlock up to level 5.
Apr: I earned 0 points and will be downgraded to level 4.