How best to structure a weekly 'drop in' meeting

I organise a weekly Zoom meeting for people all around the world to practise different languages, at the moment I just post the same repeating Zoom link (and passcode) on all our social media channels and that's how people join, however I think this a) leaves me a bit open to bad actors joining the meetings and causing havoc; b) if I ever wanted to make this a paid meeting, or send out recurring emails, I don't have anyone's contact details to get in contact.

I'm just interested to hear any ideas on how better to structure this in terms of a) safety and control; and b) going forward being able to encourage donations or offering other services to people who attend.

Should I for example set up registration on Zoom first for people to participate?