Yes absolutely a problem. I downloaded a number of the premium ‘special gifts’ plugins as I had made a donation but the four main ones i really wanted, not one worked. All required registration. Even though it is under GPL it is not a good thing. I wanted to ‘try before I buy’ as a couple of plugins I want are not cheap but in the end decided to just go and buy them – including Elementor Pro. That is one of the cheaper ones, I recommend just buying it and spare yourself the pain. Good luck.
Guys. It is not a problem, it is a feature: You get the 100% original file directly from the developers. Nothing is modified, nulled etc.. It just means that you cannot (fully) use it without the license key. If you make the effort and Google for what needs to be changed, you can customize it for your needs. Otherwise if you do not want to make this effort, you can also follow Matt Power’s advice: Buy from the developers and get a full license and support.