DiskPastActivate this PC
Install DiskPast, open Settings → License, and paste your key. Spaces and dashes are ignored. The usual shape is DP-XXXX-XXXX-XXXX-XXXX.
Activation uses one seat. Deactivate in Settings on that PC to move the key immediately. Deactivate on Account frees the seat for another PC now — the old PC may keep working about 6 hours if it is online, or up to 14 days if it stays offline. Polar Access cannot free a seat.
If you do not have the key, sign in with the Polar checkout email or see FAQ — I lost the key.
After a successful activate or refresh, you can stay offline for 14 days. Each successful refresh starts that window over.