How can i check if a certain hotkey is being held, and when is it released?

The answer is pretty simple. You can use the service "UserInputService" to sense when a key is being pressed. For example:

local UserInputService = game:GetService("UserInputService")

UserInputService.InputBegan:Connect(function(key) -- Senses when a key is pressed
    if key == Enum.Key.Q then --Change Q to any key
        --Code
    end
end)

UserInputService.InputEnded:Connect(function(key) -- Senses when a key is let go
    if key == Enum.Key.Q then --Change Q to any key
        --Code
    end
end)