No, you don’t. Trust Wallet is a non-custodial wallet and the BNB wallet address it provides you is not used by another person/persons on Trust Wallet so you don’t need a MEMO when sending BNB to your Trust Wallet BNB wallet. MEMO is only required when sending BNB to addresses on Centralized Crypto exchanges like Binance, CoinBase, Kucoin, and the likes since they only provide one BNB wallet address for their customers.