As a Stamp 4 holder you can take up employment and are not required to hold an employment permit. You can start and operate a business in Ireland. They can help you apply for or renew your Stamp 4 application.
Circumstances :
With a critical skills employment authorization valid for 2 years
With an employment authorization valid for 5 years.
As a researcher (i.e., with a valid hosting agreement) for 2 years
You may be given Stamp 4 if you are granted permission :
For joining your Irish spouse, civil partner or de facto partner.
For joining your EU/EEA or Swiss family member based on EU treaty rights.
To join a family member who has an immigration permit based on Stamp 4EUFAM
(i.e. EU treaty rights)
To join your family member who is a recognized refugee or who has been granted subsidiary protection.
To stay with your child who is an Irish citizen.
Under the investor and entrepreneur program (including spouse/partner and family)
For long-term residence.
As a Convention or Program refugee or on the basis of subsidiary protection.