When attending the marketing and promtional event/s you are able to expense the cost of the event as a marketing business expense. This will include the cost of the ticket to attend, and the travel costs to attend. If your company offers travel reimbursement, these costs are also available for daily food costs up to the limits established.
For eventparticipation itself, if your company is looking to be a presenter at an event, the costs are also categorized as marketing expenses. The costs for the booth or stand, promotional materials, staff travel and accomodations are also included in the cost of the promotion. If there is a contest, the prize amount can also be included, so long as there is no cost to enter the contest and the cost of the prize is the wholesale price, not the retail value.
Advertising in or promotional tables for political conventions or candidates, however, are not deductible.
You may find more informaiton on promotional and marketing cost expenses in this link at the irs.gov
https://www.irs.gov/newsroom/small-business-advertising-and-marketing-costs-may-be-tax-deductible