I think most type of cloud services such as DigitalOcean or AWS they let you mine with it, as long as you are a paying customer. If you got some free credits then most likely its against their rules and they won't allow it. If however you have an account in good standing then they won't have issues with it, as long as you are paying the regular rates for renting a CPU.
Generally in the past there was too many people that abused the free promo services and hence why they started to freeze accounts. They knew you weren't ever going to actually pay hence they had no incentive to allow it. Especially since you were hogging 100% of the CPU usage.
you can do mining without problem, but you can't use there free credit to mine, you have to pay with your card