The free summons you get from vip say 2x free and have no tokens involved. Those summons expire if you don’t collect them before ypu get another 2x free summons the next day.
Tokens have no expiration date and are 100% bankable. You can get a hero token today and not use it for months and it will still be there. Other tokens you accumulate in the same category will also be added to it.
There are silver for the basic summons. I accumulate about 4 or 5 of these a day on a slow day. I’ve seen players with as many as 1600. Some players use this tactic to stock up until they have multiple heros they want to power level. It’s a free feeder bank that doesn’t require space in your roster or the utilization of a training camp.