There is one, generally acknowledged (ogólnie przyjęty/ uznany) form to start the business memo:

From: ( here you put the person or the group sending the message)

To: (person or group to whom the memo is addressed)

After that:
RE: (here, write the subject of the memo)

1. Usually the memo is not as formal as the letter, however, use the common sense (zdrowy rozsądek). Everything depends on the context;
2. The memos are usually written in a friendly style because this form of communication happens between the colleagues who are equal in rank (najczęściej na tym samym poziomie w hierarchii);
3. The memos are always to the point (zwięzłe i na temat): there should be no commentaries or digressions; However, if necesssary, you may introduce the memo with a short introductory paragraph;
4. Bullet points or numbers  to explain the most important parts are very helpful as they automatically bring to them the attention of the reader;
5. Use short greeting form at the end. It doesn’t have to be over-formal.

Here is the example:
From: The Accountancy Department
To: East Division sales Staff
RE: Introduced Reporting System
We’d like to quickly  introduce you to some changes in the new quarterly reporting system (kwartalny system raportowania)  that was the subject of our discussion at  the special meeting held on (organizowany w …) Thursday, November 02. At first , we’d once again like to highlight (podkreślić)  that this new system will save you a lot of time when reporting. We do understand that you have worries about the time consumed on (czas poświęcony na …)  introducing the data to the system initially. Despite this preliminary effort (początkowy/ wstępny wysiłek), we are absolutely confident that you are going to appreciate the comfort of using the system soon..
Here is a look at the procedures:

1. Log on to the company web site.
2. Enter your ID and password.
3. Enter the information.
4. Make all the calculations in the same way as you have been doing so far.

Thank you all for your kind cooperation

__________