In case your free account came to a conclusion after the third cert expired, did you do these steps ?
Create a new free account with Zero SSL
Obtain new API key from that new account (see developers section)
Give following commands :
dashmate config set platform.gateway.ssl.providerConfigs.zerossl.apiKey [YOUR-NEW-APIKEY]
dashmate config set platform.gateway.ssl.providerConfigs.zerossl.id null
dashmate ssl obtain
dashmate stop --safe
sudo reboot
dashmate start
Verifying if cert is generated correctly by Dashmate :
Verify new cert hash that dashmate has generated with command dashmate config get platform.gateway.ssl.providerConfigs.zerossl.id and compare it with the cert hash that Zero SSL website has on their site (Certificates) by going to their cert that dashmate generated for you, pressing Copy and pasting it in notepad. The two cert hashes should match.
Also check if the HTTP port of your Evonode is green on
https://mnowatch.org/evonodes/ and by further clicking on that port you get redirected to your Evonode site where you can check if it indeed has a secure connection (click on the 'View site information' button / symbol just before your ip address on top of your site). You can fetch cert info there too.