The problem was caused by the updater, which updated P3D to the 64 bit version. The first release worked only with P3D 4.5 or 5.0, the current one has been updated to support 4.4 too so, that was your problem.
Also, the 64 bit version of the program doesn't support Esellerate anymore ( which closed in 2019 and they never did a 64 bit version of their software ), so if you got your original activation with Esellerate, when switching to 64 bit you'll have to reactivate with QLM/Soraco.
Yes, you can use your existing Esellerate keys (we uploaded them all to the QLM server), but it would be best using the new QLM keys from now on, since they also work through a firewall or even with no internet connection. You can retrieve the new keys as explained on the FAQ page.