I have multiple Macs, do I need to purchase 1Password more than once?
No, you can purchase 1Password once and then install it on all your Macs:
From Macworld Mac App Store FAQ
Can I buy an app on one Mac for use on all my computers?
Yes, you can install apps bought from the Mac App Store on any and every Mac that you personally own and use.
What about the five-Mac restriction that I have with videos I bought from iTunes? Does that work for Apps too?
No. Apps don't check to see if you've using an iTunes-authorized Mac. They can ask you to verify your Apple ID and password, but that's a single check and it's just to verify you are who you say you are. Once your identity is verified, that's it. There's no authorizing or deauthorizing or counting of different Macs.
Does that mean I could buy one copy of an app and install it on every Mac in my business?
No, the license you agree to when you enter the Mac App Store says that app downloads are for Macs that you personally own, and that's a license for personal use. Apps that are intended for business and professional use are licensed differently, typically to you or for a single computer, but used by several people. While there's no technical impediment to you installing them on multiple Macs at work, you'll be violating the license agreement. It's the same scenario as if you buy a single-user copy of iWork and install it on ten Macs at work—you can do it, but you're violating the license agreement, making the act ethically questionable.
Are there family pack licensing options in the App Store?
No, apps are purchased for and owned by a user linked to a single Apple ID. But if you log in with that ID on all the Macs in your household, you can download and install your apps on each one.
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See Macworld Mac App Store FAQ for more information.