I don't see anything in the terms of service that forbid it, as long as it is legal in your country/jurisdiction.
Acceptable use and conduct
All usage of the services must be legal
and not infringe any third party's rights. You must not take any
action or use the services in any way that might bring Canonical into
disrepute, affect the ability of Canonical to provide the services, be
illegal, or encourage illegal activities. You may not use the services
in any manner that might be libellous or defamatory (more info on what
that means), that contains threats or incites violence towards
individuals or entities, or that violates the privacy or publicity
rights of any third party. Some services have usage limitations as
indicated at https://one.ubuntu.com/plans, and you may not exceed
these. As part of the services, you may store data on Canonical's
servers or those of Canonical's suppliers. You should ensure that this
data is not in breach of any applicable law and does not breach any
individual's data protection or privacy rights. You shall indemnify
Canonical in full for any loss, cost or damages suffered by it as a
result of your use or misuse of the services.
