This error message is diplayed when the product key has activated Capture One according to the limit set by how many licenses were purchased.
For Standard Licenses
Version 9 and later: 3 concurrent activations.
Version 6, 7 and 8: 2 concurrent activations.
For Subscription Licenses
Subscription licenses allow for 2 concurrent activations.
For Multi-User Licenses
5 or 10-seat licenses are available from our e-shop and other number of seats (up to 50) can be purchased from Phase One partners.
Deactivating Unneeded Capture One Seats
Each machine will produce a unique identificaiton to our servers. Therefore, when a new machine is purchased, an OS is reinstalled, or a hard drive rebuilt, it can be "seen" as a new computer. This would require an additional activation.
To solve this error you can either deactivate a computer you are no longer using within Capture One: Deactivate inside CaptureOne or Media Pro.
If you no longer have access to a machine that you need to de-activate, you can reset individual activations or entire licenses remotely. This KB article explains how: Deactivate Online