Most sperm banks have a limit of 10 successful pregnancies for their donors and they also have limits on the number of donor sperm samples that are eligible for release in certain countries. This is to prevent interbreeding with half brothers and sisters who you may not know are related to you when the children are older. When selecting your donor check their sperm is eligible for release in your country of residence.
Related Articles:
Sperm Bank Donors
Choosing your sperm bank donor
Motile Sperm Pre Thaw and Post Thaw
How many children is a donor allowed to conceive?