I don't know what "seronizing" is, and a web search gave no answers. If that is a typo or autocorrect error please post again with it corrected, as it might help to know what was meant.
Otherwise all we have is "the app isn't working". Could be a license thing (free period ended), network problem, or anything. If you post again with a more complete description (does it not start, or seems to run but not send messages? Has it just stopped or has it never worked?) we may be able to offer more advice.
If you contact the developer they will also want to know as much detail as possible.