Please consider to draft the AUP which you may detail specifically what are the restrictions to be included. Generally, AUP is understood per Wiki: https://en.wikipedia.org/wiki/Acceptable_use_policy. Please do check at your end whether AUP is indeed acceptable as a universal reference in such website for information.
For those below 18 years old i.e. underage users, the parents/guardians will be held responsible for their access – legal principle is that those underage cannot be sued for payment save for a few exceptions including payment for necessity:-
Any recipient under the age of eighteen (18) (“underage users”) shall seek parental and/or guardian approval and consent to register and gain access at RiceBowl.Asia. Any form of proof of parental and/or guardian approval may be requested by RiceBowl.Asia at any time. For underage users, RiceBowl.Asia considers it the responsibility of respective parents and/or guardians to monitor the usage and/or response of said underage users and shall be responsible for all obligations on expense, payment, indemnity, losses and damages arising from the underage users’ access and response in RiceBowl.Asia.