Here is a summary of the daily fee details for Roam Like HomeTM:
You are only charged on calendar days you use your device (make/receive a call, send a text, calling your voicemail, use data), and you will only be charged for a maximum of 20 days per monthly bill after which time you can still use Roam Like HomeTM until the end of your bill cycle free of charge.
The daily fee covers each calendar day of usage until 11:59 p.m. Eastern Time (ET), regardless of which time zone you are roaming in.
The daily fee applies separately for each device that uses Roam Like HomeTM.