A caution will be cleared of your recored when you are sixteen if you got arrested when you were about 12-13 but if you get arrested until you will have a perminant criminal recored
(in the US) Unless your offense was committed prior to your 18th birthday, you will always have a criminal record - it does not "go away" after a certain number of years....
So-called "cautions" are not violations of criminal statutes and thus do not (SHOULD not) appear on your criminal record. In my experience these "cautions" are only kept in local files which are used...
A criminal conviction stays on your police record forever. However your question may be,"do I have to tell my employer?" This aspect is covered by the Rehabilitation of Offenders Act. After a certain...