It is not necessary to register a new domain name for shortening links if you own one that works properly. Create a subdomain using a domain you already have.
Before using Cloudflare for a subdomain, enable the service for your main domain.
When your main domain is active in Cloudflare, add a subdomain.
1. Log into your Cloudflare account.
2. Select the DNS icon.
3. Specify an "A-record", a subdomain name, and 126.96.36.199 value.
4. Click "Add record" on the right to finish.
5. Go to the Short.cm account. Click the "+" icon.
6. Choose the third option — Easy use. Click Use existing.
7. Enter a domain you already use.
8. Input a subdomain to the "Other" field.
9. Click on "Complete."
Importat: Wait a few hours and then refresh the domain status.
The video guide helps to configure a subdomain.