No. Depending on the context, it could mean for the moment, the night, the week, or possibly for a longer period of time. If you want it for forever, you would say “I will never drink beer” or “I’ll never drink beer again”.
@Jabeeee “I won’t drink beer” means it is a personal choice most likely. If your father won’t let you, use “I can’t drink beer”. You could also say, “I won’t drink beer because I am not allowed”, and that would be ok, but ‘can’t’ makes more sense here.
@Jabeeee When you say “I can’t”, it either means that you are physically unable to (such as, illness, etc.) or you aren’t allowed to. If you say “I won’t”, it’s most often that you are able to but you choose yourself not to.
@Jabeeee It could mean you would, could be both. For example: “I want to drink alcohol, but I can’t because my father won’t let me.” <- if you would. “I can’t drink alcohol because of an illness, but I don’t like it anyway.” <- if you wouldn’t. “I can’t drink alcohol because it’s bad for me.” <- this one is awkward, and not often used, because can most often means ABLE to. So I wouldn’t say this.