I have a collection of fonts from OPTI Fonts by Castcraft Software that I purchased in the late 1980s or early 90s. I can't find the receipt or the original 3.5 hard disks. Its been close to 30 years. Its been over 25 years since I had a floppy or 3.5 hard disk drive. It appears the company no longer exists. Can I still use these fonts if I cannot demonstrate I have a license.? I am trying sort out my font collection. 

The ethics of using OPTI fonts go beyond having a license for them. That said, unless you plan to use them for something akin a corporate typeface for a client, I don’t think there are particular problems. But also I’m not a lawyer.

I was not aware these fonts were pirated. Were they copies of typositer fonts or copied from old specimen books?

Here is a link to a short history of the company:

http://luc.devroye.org/fonts-27506.html

Castcraft was notorious for pirating Typositor film fonts back in the seventies. They contact-printed fonts originating from other producers, changing only the name. I saw one of their catalogs around 1980 and it was a ring binder about 2 inches thick, with five or six fonts shown on each page. You could get practically anything from them. I recall noticing that in some fonts, there were characters upside down or backwards. Producers of fonts would do this deliberately on a single copy of a font to be sent to a type house in order to see where the pirated versions were coming from. The OPTI Fonts collection was drawn from Castcraft's vast collection of pirated film fonts.

OK. I will not use them. I have not used an OPTI font since the 1990s anyway. On a side note: I had a part time job when in design school setting headlines for a magazine using a typositor. That was in 1981-1982. The art directors liked insanely tight letter spacing. You could overlap letters with that device. 

Thanks for the info!