ServiceApiException when extracting html to PDF

Hello, 

We're receiving error ServiceApiExcepption after getting bytes[] from converting html to pdf. Sometimes it works without throwing any error but somtimes when converting a lot of data it thrown error. Is there any limits or quota in converting even if we have a licensed.    

Please see the image below for error: 

Also there are instances when converting become slow in this part and error thrown after: 

Thank you!