As to which version, it depends on whether your computers meet the minimum recommended specs.
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As to cost of a single licence, you will have to check on the website of a Blackmagic reseller in your country.
The license is a one off charge. No extra charge for updates has been made by Blackmagic since at least version 8, though they reserve the right to introduce a charge if they need to.
A dongle is like a usb pen drive which will activate Resolve on a computer it is plugged into.
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If you unplug it Resolve will stop working until it is plugged in again. It means you can have Resolve on any number of computers and by plugging in the dongle activate it on that particular machine.
The activation code will authorize two computers at the same time. If you activate on a third one it will cancel one activation automatically. You will always have two activations available.
Discounts would be up to the reseller not BMD. The best deal at the moment is the inclusion of the Speed Editor for free when you buy the Studio version of Resolve.
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