A pack is $9.99 for 40 portraits on up to 4 pets. That suits most households.
Heartgild Pro is $99.99 for 600 portraits in every theme, for unlimited pets. It is built for groomers, shelters, photographers and anyone making portraits for many animals.
Both are one-time purchases and never expire. Credits are stored on your device.
If you are making portraits for one or two pets, a pack is enough. If you are doing a whole shelter, Pro saves money.