Starter plan (Free)
1. Add upto 10 users to the account
2. Run upto 10 projects
3. Maintain upto 3000 test cases
4. Limited features
Pro plan (Paid)
1. No cap on number of users. You pay by the number of users you have.
2. Unlimited projects
3. Unlimited test cases
4. You get all features
See the full comparison here.