Possible Clues:

• A lot of memories? Some of them get by in 21
• 1,048,576 units of computer information
• Lots of little bits spoilt game by Lawrence
• Storage unit
• 1,048,576 bytes
• Hundreds of thousands of words, maybe, get misused
• Entry secured by following setter's computer space
• Unit of computer memory; gate by me (anag.)
• Amount of computer memory - get maybe (anag)
• Mb expanded