I would like to turn off the Preview Limit pop-up. How do I turn off the pop-up?

You can enable or disable the Preview Limit reminders any time from the Account Settings area.

To get there, follow these steps:

From the Home Feed, tap the person icon at the bottom-right of the screen to open your Profile.
On your Profile, tap the gears/wheel icon near your designer information area to open the Account Settings.
On the Account Settings page, scroll down until you see the setting for "Preview Limit Reminders".
Switch the "Preview Limit Reminders" setting on or off, depending on which you prefer.