Hi ,
Firstly ,welcome to the forum ,
I have read through this thread with interest and see that most of what I can say has already been said , just to add my two pence worth though I think your glass is English and lead glass , the ridge you can feel on the bowl rim is quite normal and is down to the fire polishing giving it a more rounded and softer feel, a folded foot is no indication of age I am afraid, glasses with folded feet can be 500 years old or 5 days old,these types of glasses are fairly common and I would suspect yours dates anywhere from 1780 to 1820 give or take a little either way for the reasons already given by others, what were they used for ? , anything you like I say , there is very little documented evidence of glasses being produced for specific drinks like Gin and Port until the later 19th century and most of the attributions given today are guess work except for some like ale and beer glasses and cordial glasses etc , small glasses like these would I think have been used for stronger spirits, so yes Gin Whisky Port etc are all possible candidates.
Being inexpensive these little glasses are a great area for collecting without laying out fortunes and you can enjoy your favourite tipple from a glass getting on for 200 plus years old .
cheers ,
Peter