A 5-day plan vs a 7-day plan
A 7-day plan charges you for the two days you missed. A 5-day plan leaves you two days off.
In Bibliou the monthly plan is 5 days a week. The message says: “Your November plan. Five days, no debt.”
You can reply “change to 7” if you like, but most people go back to 5 by the second week.