- Lay is a transitive verb. You can’t just lay down. You can only lay something [down]: you can lay foundations, you can lay a baby in a crib, you can lay a carpet, you can lay down the law.
- Lie is an intransitive verb. You can lie down. Lay is also the past tense of lie.
Probably a good word to avoid, in the main. It’s over-used as a verb meaning to use or take advantage of or benefit from, as in “we will leverage our market position”.
The noun is licence; the verb is license. If you have a driving licence, you’re licensed to drive.
Life expectancy is the average period that a person may expect to live. You don’t usually need to say “average life expectancy” because that’s nearly always a redundancy.
login, log in, logon, log on
One word when used as a noun or adjective; two words when used as a verb. Once you’ve got a login, you can then log in (using your login details). And it is log in / login (which is current) rather than log on / logon (which is a bit dated). And you log in to a website or account, you don’t log into it.
Hyphenated as an adjective; two separate words as a noun. Your long-term plans define what you will do in the long term.