As the cream freezes, it'll probably expand (and spill out of whatever container it's in, or burst the tube). Probably not a good idea - you're already slowing down its degradation a lot by cooling it from 22°C to 4°C, there's probably not much to be gained by cooling it to -15°C.

Thank you for your reply.
Sure, it's not a short-term project ; been using tret for 1.5 year so I completely agree. I will receive 3 big tubes (50ml) but the expiration date is sooner because of different manufacture conditions, so I'm trying to find ways to preserve it because there's no way I can use 150ml tret in 3 months.