The update wss offered, and installed normally; I was not asked for the key - I bought a £10 "life" key about 8 months ago. Seems to me it is worth having the latest version, as they, presumably, must think it has improvements.
The first is the version of the malware database and the second is the version of the program. You need to update the program to the later version as it has several improvements. Just accept the update and it will self install.