No it should be almost immediate, but there can be occasional delays, ensure that you monitor emails if you have an anti-spam program.
If you have just installed it you should have 60 days unrestricted use, by using the Demo key. You don't have to have a registration key straight away. Give it a little time, if you don't receive it you may assume that a spam filter may have got it.
You can register again, if you use the same email address that you did previously, you should receive a copy of the original one. If you have another email address you could register again and use that and you will get a totally new registration key. Whatever you do watch out for spam filtering.