If you don't have Qonversion User ID when you want to make a purchase, you can create Qonversion User ID while creating an identity.
- Create or get Qonversion User ID:
* Create it by yourself with create User ID method
- Create by creating an Identity without the Qonversion User ID parameter. Use create Identity method.
- Get it by requesting existing Identity. Use the retrieve Identity method.
- Create a purchase.