When moomoo says commission-free trade, does it also mean commission free when selling my shares?

Yes. But do note that moomoo (last I checked), does charge other fees despite being 'commission-free'. This is due to the platform fee charge on moomoo which is separate from the commissions. As such, while commission-free, the trade is not free. When I sold the free AAPL share, I was charged USD1.00 for the platform fee and anothe USD0.09 in GST and other taxes/clearing fees.