If any of the plans increase in price, as long as your membership hasn’t cancelled, you will be billed your original amount.
For example, if you currently pay $5 per month and the monthly subscription increases to $25 per month, as long as your subscription remains active, you will continue to be billed $5 per month.
If subscriptions cancels, and you resubscribe at a later date, you will pay the amount applicable at that time.
If you upgrade from a Monthly to an Annual Pass, you will pay the current fee for an Annual Pass.