two choices
- ignore the registration. after 50 uses or whatever it is, it will revert to runtime
- register, which breaks copyright. MS do let you overlicense products. eg You are allowed to install office on both a desktop and laptop as long as you only use 1 at a time. there are also legitimate reasons for reinstalling - eg, computer breaks, and gets replaced. So MS will certainly accept a number of registrations on the same key, but at some point will refuse to register the licence key, when it has been used too often
Now You wouldn't want to over-register properly licensed software especially when you are a professional developer - but this just clarifies exactly what happens.