Frame it as a service charge expense, not a subscription. At £1.50 per unit per month, the whole building is covered for less than 15 minutes of a solicitor's time.
For RTM directors: at £1.50/unit/month, the block subscription costs less per leaseholder than a single WhatsApp message to a solicitor. Run it through your service charge budget. Most blocks can approve it without full committee sign-off.