Unfortunately this game has limit of 3 online activations.
The activation gets revoked as soon as you make a minor change to your system, such as adding more ram etc. Afterwards you will have to activate again.
If you have used up your 3 online activations, you will either have to email the developer or ring an international number before you are allowed to play the game you paid for. Just hope that the company doesnt close down, which means you have a nice frisbee somewhere down the line.
Very dissapointing because I far prefer to play this type of game on the PC. The developer of this game has lost another sale due to an unreasonable DRM scheme.