1.
I bought AdGuard VPN lisences. I installed the Firefox Add-on), and the Window ver too.
Adguard have sync, e.g., Adguard window ver. <-> Adguard browser add-on.
However VPN doesnt sync. Further it take lisence. Thus when you install Ad.VPN(OS ver.) and Ad.VPN(browser Add-on), you use two lisences.
I hope to fix this defect.

2. The important thing is, browser Add-on works better than Ad.VPN(OS ver.)
Ad.VPN(OS ver.) works on every browsers and programs, but sometime it shutdowns.
Ad.VPN(browser Add-on) works on only its browser and consumes lisence, but rarely shutdown.

After all, I uninstalled AdGuard VPN(OS ver.)