Kill VPN account after 50 MB of transfer?

I want a way to have the box auto Kill a VPN account after it does 50 MB of transfer.

Can anyone think of a way to do this on a Routeos v3 box?

I often make temporary vpn accounts for users, and have scripted an easy interface to do this for myself. however id like it to auto remove them at 50mb of transfer.

tks

Create a simple que running on the vpn interface and check it’s traffic stats each minute. Whenever it’s reached your limit disable the vpn interface or erase it, etc.

what authorization method do you use?..