Three things:
1) A single user license lets you install on multiple computers for your own personal use. Each user does need their own license. If you have two Macs, just install 1Password on each of those two Macs and sync it up using iCloud or Dropbox. We also sell a Mac+Windows bundle on our site for users who have both Macs and Windows PCs.
2) The mobile apps are full featured applications as well. If you're at a friends house you can type the password in by hand from your iPhone or iPad. Not sure about you, but I always have my phone on me and in a pinch, that works just fine to use the 1Password browser to login and access data if needed. It's rare this doesn't work for me. We have a full featured Android application coming soon.
3) If all else fails, there's also 1PasswordAnywhere, you can see that here:
http://learn2.agilebits.com/1Password4/iOS/Tutorials/ios-1pa.html
That's my preference order as well. I have 1Password installed on each of my computers, and in my Windows VMware image. These are all synced up to the same data files. The mobile apps are probably used less by me personally but many people use it quite a bit, it's just my personal workflow tends to be mostly on a computer. When all else fails, 1PasswordAnywhere works well in a pinch.
Just be aware, you should never type your passwords into a computer you cannot say you fully trust. That means cyber cafe shops, particularly in other countries. I wouldn't touch these with a ten foot pole. Any traveling I do I use Cloak VPN service and my mobile devices as hotspots or access points.
Please let me know if this helps or if you have any questions!