There are two type of policies when it comes to new releases.
Some companies like Symantec and Kaspersky will release new versions each year, and in the mean time, if their is a need for an algorithm to be improved, they will just send you a Service Pack.
Other companies like Avast or COMODO, instead of having a 2013 or 2014 edition, they just use a simple number to define their version, so they don't need to wait 12 months before releasing a new user interface and features upgrade.
- Symanatec (Norton) releases their products in September
- Kaspersky usually release a new version in July or August.
- ESET just released their 6th version, and like in this case, they will update their products in March or April.
- G-DATA release their product in April or May.
- Bitdender will upgrade its line in July or August.
- F-Secure releases their new product in September or October.
- Avira will release a major upgrade in September or October.
- Emsisoft, COMODO, Avast and Outpost will release a major upgrade whenever they are ready, no matter or month it is.
No matter what product you have chosen, once a new version is available, the vendor will allow you to upgrade FOR FREE to its latest build.
You should always use the latest version of software available, because with each version, you'll get some significant improvements.