You can save projects, but you cannot reopen them until you purchase a license.
Modern versions (FL Studio 21 and later) primarily use account-based sign-in for activation rather than standalone registry files. fl studio 20621549 executable reg key free version updated
Be cautious when searching for "free" versions of FL Studio or updates that claim to offer full functionality without purchase. Officially, Image-Line offers a free trial, but for full access, a purchase is necessary. You can save projects, but you cannot reopen