I am not from Laminar Research; just a flight simmer from downunder.
You will not get your problem solved in this forum irrespective of where you purchased the digital down load.
If your copy of X-Plane is a Steam version then you need to deal directly with Steam. The steam version is a 3rd party hybrid (modified) version of X-Plane. A different product that installs differently to the original and official version of X-Plane developed by Laminar Research It is not sold by Laminar Research
There is also a version sold about 12 months ago by the "dodgy brothers" where by it is a pirated copy of x-plane or a pirated product key is supplied. The software crashes immediately after 1 use. You then need to purchase a complete official version of X-Plane.
If you have purchased your official download version directly from the developers, being Laminar Research, then you have to be connected to the internet at all times to run the software. The software performs a silent background check to verify the software you are running is an authorised version and compares it with the product key or activation key you have been supplied with. If you don't connect at all times your system will most likely shut down. If you have been connected to the internet at all times then your problem should not have occurred.
If you have a Laminar Research version then you need to contact Laminar direct at Keyrecovery@x-plane.com or firstname.lastname@example.org to solve your problem. When you do, make sure you provide full details of your problem rather than the scant information supplied in your originating problem shown above. You will also need to provide details of the email address used when making the purchase, Details of the method of payment and when the purchase was made. Details of receipt numbers issued by Laminar Research. Details of the activation/product code supplied at the time of purchase.