In short, every state has different laws regarding the amount of time you need to keep your SR-22 insurance, so in short, check with your state and local laws. Here are a few samples that may be outdated by time you read this:
Florida: 3 Years
If a judgement is issued, then this can be lengthened to 20 years until the judgement is satisfied (which is automatically the case if you were driving without insurance).
Texas: 2 Years
Colorado: 3 Years
9 month – 3 years, depending on various criteria, such as, if you were involved in an accident, and other various factors.
Additionally, the SR-22 must be kept for as long as the duration of the revocation, or sometimes even longer if the person was involved in an accident or other early reinstatement.
Remember, if you do not keep your SR22 up to date, your insurance company may immediately notify the DMV and suspend your license.
Again, check with your local DMV/court/gov. to be sure on current SR22 requirements, rules, and regulations.