Eligible voters need to hold coins on relevant blockchain. A snapshot of coins balances is taken at a block height relevant to the proposal, e.g. 7 days before the start of the voting period. Voting power is then based on this snapshot. Coins can be moved or transferred after the snapshot is taken, only the balances at the snapshot time are considered for voting, preventing the same coins from being used multiple times. When voting, you provide the address holding coins on the 7th day before the voting period. If you wish to implement this voting system for a DAO contact us for further details.