Technically the word LEGO® is always written in full capitals because it’s a trademark.

The LEGO name is always spelled in all capital letters and the bricks (and/or elements) must always be referred to as “LEGO bricks” (or “LEGO elements”) – never “LEGOs” or “legos”.

And

The first time the Trademarks appear in a headline and in the following text, they should be accompanied by the relevant symbol: the LEGO trademark and SERIOUS PLAY by the ®symbol

Thereafter, the symbols need not to be used more on the same page, or in the same chapter.