See here:
https://www.eurekareport.com.au/investment-news/schrole-group-a-school-recruitment-platform/147523
Alan Kohler interviewing Rob Graham, Schrole Group's Founder and CEO, in June 2020 (two months ago):
Excerpt from interview:
AK: It’s possibly a good opportunity now to just explain your business model. You've got a recruitment platform and you get money from both sides: the schools pay you and the…
RG: Candidates, yes.
AK: …and the individual teachers pay you as well, is that correct?
RG: Correct. Everything's an annual subscription base. Schools pay to be on the platform and that's a charge based on the size of the school with the number of teachers they have, and the expected amount of teachers that they'll turnover. And teachers have the opportunity to come on a platform for free but if they want to do anything like search for jobs, or get notified about jobs, they pay an annual subscription, and that's been very successful as well. We've had 6,000 teachers paying US$75 dollars in the last 12 months and that number is growing every year.
AK: In your model, which is the chicken and which is the egg?
RG: Well, I actually think it's funny, it’s probably more the candidates. The more candidates you have the more schools you can get. Having a really rich and deep candidate database is probably where everything comes from. It's not how we started. We started selling a platform to schools, but we sold it to really good schools and before we knew it we had 10,000 candidates on our platform and that became something to attract other schools.
AK: Right. As long as you've got the candidates, you're saying that the schools have to be on your platform, is that correct?
RG: Yeah. Well, look, I think we’re a really cost-effective solution for schools because they know every year what they have to pay for us. For other platforms, they'll have to pay a recruitment cost per teacher. And so that can be upwards of, you know, a percentage of revenue or a fixed fee, but it's certainly more expensive than using our platform.
--- end of excerpt ---
So, yes, it's clearly an annual fee, so schools can NOT "turn off" mid-year. I believe ARR is absolutely a valid valuation tool for SCL.