Generative artificial intelligence systems should be carefully tested because they can generate low-quality content, but the testing challenges the test oracle problem. Metamorphic testing helps to test programs without test oracles. In this study, we consider an AI system that generates personalized stickers. Personalized sticker is a thematic picture with a person's face, some decorative elements and phrases. This system is stochastic, complex and consists of many parts. We formulate requirements for the whole system and check them with metamorphic relations. The requirements focus on dependency on input images quality and resulting quality of generated stickers. Our testing methodology helps us to identify major issues in the system under test.