Can I Include Resell Rights with Instant Downloads Lists?

Can I Include Resell Rights with Instant Downloads Lists?

Hello when I sell a list of something as an instant download.

Can I include some resell rights with that list?

Like can I state that no resell rights are included?

If it's my own work that I've worked hard on.

Do I have to state this somewhere to make it official or is it just a general rule or not?

Do you sell lists of things and include resell rights?

There is a buyer who has bought my lists and is reselling them on other microgig sites and undercutting me.

I never gave my permission to do that but I never stated they couldn't either.

However not stating they cannot doesn't automatically give them the right to resell them anyway, right??

I feel cheated and as though its not right as that was my hard work that went into that and they don't have the right to resell it in other places, under my nose without my permission. Expressed or not.

What say you?