Microsoft 2013 Subscription licence keeps expiring

hi

I have user ,whose office 2013 keeps expiring every few months , i have reactivated it using ospp.vbs command

but it keeps happening often.

I have also unlicensed his office on 0365 and re-licenced it but still the same problem persists

Also uninstall and reinstall office and done repair

can anyone suggested a solution to fix this problem permanently

Regards

Rohan.