i want to buy your software but i have 2 user ids. do i have to buy 2 times?

Hello K,

You are allowed to use it for as many user ids as you need, as long as all of them belongs to you or under the same household.
You have to activate the software using user id when you bough it, then you can re-login as another user id and continue using it.
Please feel free to ask if you have more questions about this.