I have so far found out that an account needs to have a trustline for an asset if it is to receive a payment of that asset (from a given issuing account).
Does an account need a trustline for an asset if it is purchasing it on an exchange?
The reason for me asking this is that I can set the trustline for accounts that I create in my app, for the purpose of receiving transfers of my token within my app. However, I'm wondering how this would play out if an account created outside of my app, hence without a trustline to my token (asset), would be able to purchase my token.
I am new to Stellar dev, so I could very well be missing something obvious in my understanding of the process.