Hello AnaskinSecco57
What stampede writes is the correct procedure. Also look in DaVinci in the menu bar under "Help" whether your licence is activated or deactivated, then you know that you have to do the way of stampede.

Try this solution: go to your Davinci Resolve account and to your products. Deactivate all saved computers there. This will release your licences again. When you restart Davinci Resolve, the programme should now ask you for the activation code.