DecisionPad licenses are assigned to an individual person. You can install the software on whichever computers that person uses, as long as they are the only user. If additional users are needed, you just purchase each of them their own license.
Balloting (new in version 4) requires a folder on the Apian cloud server for each decision project while it has ballots open. One folder is included for 90-days with purchase of each software license. After that you may rent them by the month as needed.