The license allows for it to be installed on 2 computers. Acrobat Help has this to say about activation, U.S.:
"A single-user retail license activation supports two computers. For example, you can install the product on a desktop computer at work and on a laptop computer at home. If you want to install the software on a third computer, you must first deactivate it on one of the other two computers. Choose Help > Deactivate."
You can find a copy of the license under the Acrobat application install location folder Legal and there will folders for various countries and languages. Look under Software License Section 2. for the exact details for your country and language.