If you are a sponsor you should receive your sponsor database email, no?
Dear, here is Hunky City... lol
If you purchased Dead Dating on itch.io, you just need to send an email to service@fymmg.comThen we will send you an R18 DLC key. ;)
1. Click the DLC section on the title scene.
2. Click the activate button on the last banner.
3. input your key manually
4. Start a new game. ;)