Memo, Destination Tag, note or comment to the payment – an additional option of the address in the details, mandatory to fill in. This label serves as the identifier of the client who transfers funds to the address of the service or any platform. Memo, Destination Tag, note or comment to the payment is used in those networks where it is provided by the mechanics of the network itself, such as Riple, Binance chain, Stellar, Toncoin and others. When transferring funds to personal wallets, the label is not required. But if you are asked to specify it, then it must be done. Otherwise, you will have to prove that it is really your translation, and not someone else's.

Why is this happening and what is it for? Large services can use one address for receiving and identifying customers by an additional universal number that is assigned to the customer by the service system when forming an invoice for payment (providing details). When transferring funds to an address and having registered a label, the data is transferred to the blockchain, information on crediting with a label is transmitted to the owner of the address. This label indicates that the transfer is yours and the transaction is being processed.

You can take an example from life. You want to send a letter, you have registered the address, the house number, but you forgot to register the apartment. Such a letter will return or will lie in the general pile until it is requested. In this example, the apartment number is an identifier. Similarly with MEMO. If you have not specified a MEMO, then the funds will lie in the general pile until you contact support with proof that this is your transfer.
Be careful, do not forget to specify the full details when transferring. And remember that you work with money.