Hello, @jouo

You will never be billed more than the monthly cost of your Droplet. All Droplets are billed hourly up to a monthly cap of 672 hours (the number of hours in 4 weeks). If you use your server for fewer than 672 hours during the month, you will be billed for each hour that you used it. If you use your server for more than 672 hours that month, you will be billed at the monthly cost. For example, if you spin up a $10/mo Droplet and use it for 336 hours, then you would be charged $5 (going by the hourly rate). If you use that Droplet for 700 hours, then you would be charged $10 (capped at the monthly rate).

If you choose the RAM only upgrade you can always switch back to the previously used droplet’s specs at any time.

Hope this helps!

Regards,
Alex