What is Next Free Episode
Gauge Bar (Purple)
You can find a gauge bar on the top of the episode list for a given comic series. When your gauge is full, you can read rental episodes (episodes will display "read now" on the right)
Gauge Bar (Orange)
Most gauge bars are purple, but some will be displayed in orange (with the display "next free episode with ads" on top). when the orange gauge bar is full, you can read a rental episode after seeing an AD.
Refilling Gauge Bars
You'll realize once you've consumed a rental episode using a full gauge bar, the gauge bar will be empty. The gauge bar will fill up again after a certain time, and the time required until the gauge bar is full again will be displayed on top of the bar.
Using Tickets & Coins
If you have a ticket, you will use up the ticket after using up the gauge bar. Tickets can be used to access rental episodes regardless of whether the gauge bar is full or not. For further details regarding tickets, please refer to the article:What is Ticket
You can also permanently purchase a episode using coins. For further details regarding coins, please refer to the article: Unlock episode with coins