Getting Error related to INVALID_PLAN_CODE

My Request Tracking Id is "cIPgW4sfWl1ENiRD7XlgHq1AiE6yZnKi" I have been using the PDF Services PDFExtract API from some time but today it showed me the error

"adobe.pdfservices.operation.exception.exceptions.ServiceApiException: description =Unauthorized to execute this operation. User is not enrolled to plans allowed for the service; requestTrackingId=cIPgW4sfWl1ENiRD7XlgHq1AiE6yZnKi; statusCode=500; errorCode=INVALID_PLAN_CODE" Please resolve my error i have given the request tracking id above at the start of description.Also using the same API key from different computer it works fine but from the computer i have been using for long time the API gives the above error. Please Help