Stim, I'm sure the pub owner will pay the ASCAP licensing fee as soon as she gets the pub going strongly enough. It's a very new venue for live music (having been a different kind of bar for several decades before she bought it), and things like karaoke, open mics, song circles, etc., don't bring in much more business - so far - than she'd have with just the juke box and the other attractions (TV, video games, free pool tables, and a great selection of potables and food at reasonable prices).   The only nights that really pack 'em in, so far, are the ones where she gets some really good bands (with rock, jazz, rockabilly, etc.)
Some of us would like to get an actual jam (fairly unstructured) and/or open mic going, and it probably will in time bring in a lot of business, but we've been asked not to do ASCAP songs (though some of the bands obviously ignore that). I'd just like to avoid the ASCAP songs if I have alternatives that are either PD or at least with BMI or SESAC.

Joe, you're right about ASCAP not paying the songwriters what they deserve to be paid. That's what irks me.    I could get up there and do Townes Van Zandt or Jimmie Rodgers or Greg Brown or Carter Family songs and I doubt seriously that any of those artists (or their heirs) would see a penny from ASCAP for it.

I had thought that pre-1922 songs were PD, but it's obviously not always the case.   "Happy Birthday," for instance, goes back before then, I'm pretty sure, but it's still under copyright.   A lot of songs written before 1922 have had their copyrights renewed since then.   

I'm interested in the ASCAP info not just for this venue but for general reference (e.g., singing in other public establishments).