Each user will be provided a checking quota, the quota is tracked by  bar on the home screen. The checking quota consumption is based on the lines of codes being run into the checker. For example, a file with more lines of codes would consume more pro checks. The checker will intentionally fail the checks if the user doesn't have enough pro checks inside their account. If you receive a failed checks message, make sure you have not gone beyond trial consumption. In that case, you must upgrade your pro account by going to the billing section.