Bothering people with deactivation is not a good approach. People who pay for the app shouldn't be limited at all with things like this.
Licensing system is very 'loyal', it means you can reinstall it as many times as you need and also can install it on additional PC's (eg. backup system, your home system, laptop etc). Unless you exploit the system, eg. give away your key to friends or publish it somewhere on forums, you won't have any problems with it.
