If you use the free tokens you have (about 500MB of data each) they will go into your Token Bytes Bucket.
Should you need to purchase additional tokens such as the 3, 5, 10, or 25GB token, then they will also be applied to your Token Bytes Bucket. Tokens are not used unless you have exhausted your bandwidth for a certain time period... To make it simpler, lets imagine three buckets, Anytime Data, Bonus Bytes, Token Bytes. Depending on the time period, we would arrange our buckets in a certain way in the order they are used.
8:00AM to 2:00AM would use your Anytime Data first, once that has exhausted, you will start using your Token Bytes
2:00AM to 8:00AM at night, you would use your Bonus Bytes first, then your Anytime Bytes, and finally if you have exhausted both of those, it would start dipping into your Token Bytes.
Bonus Bytes can ONLY be used from 2:00AM to 8:00AM. If you use all your anytime bytes up and have bonus bytes left, then your speeds during the bonus hours will not be impacted, only the anytime hours will be impacted.
You can purchase your tokens at any time you wish, they will not be used till you have exhausted one of your buckets, and any remaining token bytes will roll over. Your Anytime and Bonus do not roll over, and can not be interchanged nor traded. You do not have to purchase tokens, however, speeds will be throttled back to approximately 1Mbps or lower if congestion for your beam is bad.