When you activate your Bivy Stick, you are given credits to use. Each credit is basically one action of the Bivy Stick. 1 credit = 1 message, or 1 location share, or 1 weather report, or 1 hour of tracking. Preset Check-In messages, however, are unlimited and free. Your credits are valid for as long as your Bivy Stick is active. If you use all credits and are way off-the-grid out of service, your device will still work great and you will be charged $0.50 per additional credit used. If you do not use all of your credits by the end of 30 days, and you pay the monthly base plan to keep the device active, all unused credits will rollover and are available to use later.