what if tea leaves are kept for more than 4 years

Hi, it depends on the types of tea. For example, some tea are meant to keep for long, like Puer Tea, black tea, etc. Green tea should be kept no more than one years. Also, it depends on the condition how you keep the tea. If they are sealed and kept in good condition, it is fine. I suggest you try to make tea. If tea leaves are still leaves, I mean they do not go moldy, and the color of the tea doesn't turn into dark and red, they are still possible to drink. Pay attention to the production date and drnk it before the expiry date. I am not sure about Swee tea in fact, for this name is not familiar to me. However, I think 8 years are too long.

if your tea is green tea, it can not be kept very long. if your tea is puer. it can be kept very long. so we don't know what kind of tea do you have ? i am a tea producer.