I bought GSX Level 1 for FSX from Just Flight back at the end of 2014. I have the order details for that.
In the middle of 2017, I made the step up to P3D and after that had GSX Level 1 running in that simulator. I can't remember though how that transition worked. Was there are free upgrade? Or a discounted purchase? Or did I buy the whole thing again?
I've just had to do a full reload of P3D and I can't for the life of me remember how to re-install GSX Level 1.