Membership expire in 1 hour text

I have a website were I want to use one time payments in combination to subscription plans. I use them both in combination with MyCred for them to gain Coins and unlock content.

I want to use the one-time payment as a way for them to buy additional coins if what they get from the subscription plan isn’t enough. But I see that a text shows when a plan is one time payment that tells the users that it expires. How can I edit that text? Instead of expiring in 1 hour, it can be purchased again in 1 hour.