If the add new lead button is grayed out in your account this can mean one of the following things:
- Your Kommo subscription or trial account has expired
- You have exceeded the number of available active users according to your plan
- You have exceeded the available number of contacts and leads
You will be able to diagnose the issue by going to Settings -> Billing. In the top you can read a comment on the status of your account. Depending on the cause, you can unblock the account by disabling a user, deleting leads or making a new subscription.