This article applies specifically to the UK, but may also be relevant elsewhere in the world. And if you live in a country where you can't currently get royalties from your live performances, you might consider campaigning so that in future you do!
As you may know, any commercial premises in the UK where music is performed - live or recorded - has to pay a licence fee to the Performing Right Society (PRS) or PRS For Music, as they now style themselves. This applies not only to music venues, but hairdressers' salons - for instance - that have a radio on, and factories where music is played to the workers. Where music is used for the benefit of a business, that business has to pay the PRS licence fee.
Money collected by the PRS is distributed among their writer and publisher members. So if you have written a song and it is performed in a commercial premises, you are entitled to receive a royalty.
The problem has always been how to track each and every performance of each and every piece of music that is registered with the society. Clearly, not all performances will be tracked. It just isn't possible. So the money collected from untracked performances is distributed pro rata according to performances that are tracked.
But in the online world, it is much more practical than it used to be to report performances to the PRS. And you can report performances of your own music, even if you are the performer.
First though you'll have to become a member of PRS. You can only do this if you have written music that is likely to earn money. Once you are a member, you will register your songs with PRS. Then you can start actually earning that money.
If you perform your songs at a concert venue or festival, then you can submit a set list under the 'Concerts and Festivals' scheme. If you have played at a pub, club, bar, community center or hotel, then you can submit your set list online. If you have covered someone else's song somewhere in your set, then include that so the writer can get paid too. Fair's fair.
You can even claim for performances that took place up to a year ago. PRS publish a list of unclaimed live performances. There might be money with your name on it, just waiting for your claim. If you don't claim, it will be shared among the rest of the PRS membership.
In summary, if you create music and it generates money in any way, you deserve to be paid your share. PRS will help. If you don't live in the UK, look up the collection society in your own country. If you don't, you might be missing out on $
millions, $ thousands, $ hundreds... Beer money? :-)