Im using Professional Edition.Is there anyway to use long text area in formulas. Im searched most of the links but i didn't get any answer. Please tell me how to resolve the issues.
No, there is not. There is an Idea to support it here. In the comments for that Idea, there is a workaround described (and also linked to and described here) that uses workflow, but that isn't available in PE. I can't think of a way to do it in PE without an API integration, which requires PE API access enabled at additional cost.