Too many machines error after AWS Lightsail snapshot restore

I'm currently testing CPanel on AWS Lightsail. Although Lightsail enables you to create and restore snapshots, it seems that this can't be done without creating a new CPanel instance. That's fine except that after I've restored a few snapshots (ie created new instances), I get the the "Too many machines" error, presumably because each new instance counts as a machine. This could be a problem. I'd like to know how many instances I can create before running into this error & is there anyway of fixing it quickly without having to contact support?