Premium features

Hello,

Yesterday my games were promoted automatically but now the game want me to use protocoins. I don't get it because I purchased for 1 month.
Do I have to buy protocoins even if I am premium ?

Yes.
it doesnt matter if you're premium or not to use the promote button you need to have spare of 50+ protocoins in your account

Alright thank you, I have another question about the premium features:
If I choose to disable the upgrades will I be able to use marines ? I guess it's no but maybe they are allowed with strategies like GW who needs it ?

Correct if you choose to disable upgrades it will disable every upgrade you have but when you use a certain strategy it will give you the units it require to operate (not every strategy)
like: GW - unlocks marine and militia
Master of Stealth - unlocks Stealth but not marines and submarines