As a Steam user, I can honestly say that I've not had any issues with Steam's version of Construct 2. With Steam you're automatically registered when you download it, all you have to do is sign into steam. It works fine on both Laptop and Desktop for me. Having more than one instance of it open at a time seems unnecessary, unless you're working on more than one game at a time, which sounds problematic to imo.
I bought the Steam version after much consideration and I haven't regretted the decision, but you should also weigh your options before you make your decision