I am useing it on Firefox and it does not stay signed in all the time

Not always working.

I keep on downloading it in my system and it keep keep removing itself from my computer.

Works intermittently on Firefox Quantum 62.0.3 (64-bit), therefore I question the point of paying for a premium service.

Uses too much ram. Its nearly impossible to use it on outlook. There is too much emphasis on UI and very little attention is paid to UX.