Thank you very much, regardless of whether the conference fee invoice is issued by the hotel or the conference company.

According to the Measures for the Administration of Ballot in People's Republic of China (PRC)

Twentieth units and individuals to sell goods, provide services and engage in other business activities, foreign business to collect money, the payee shall issue a * ticket to the payer.

So from a legal point of view, the payee should open a ticket, and whoever receives the money will be responsible for opening it for you. In actual business, there are also cases where conference companies directly give hotel tickets to payers in order to avoid taxes.