This game is limited to be played for 5 years. However, you can at any time decide to Sell Out if you think you can't do better. Its very important to Sell Out (Work screen, option 6) before you go bankrupt, or else it will show on your final score, as you'll see if you check out the Scoring System Formula below.
As said its only allowed to play for a maximum of 5 years, any longer and your recording will be DQ'ed. When it says 1:12:88 on the Software Inc. screen, then you have played for the allowed 5 years, and you must Sell Out to get your final score. You do that by going a few screens further into the game, until you get to the Work screen. Here you choose option 6 to Sell Out. Now you'll get to the Score screen where you'll get all the information you need to calculate your final score.
In the Stages field you must insert the number of Months you were in Business.
Selling Price + (Time in Business * (Popularity + Score))
Millionaire Regulation Play calculation help: